Step Grandmother overstepping boundaries, how do I handle this?

Hi! I am new here and thank you for allowing me to join. I have a huge problem and don’t know how to handle it. I have to give a little bit of history for you to understand. I have 2 daughters from my first marriage. We married very young I had my first daughter when I was 27 and the second when I was 18. My husband was only a year older than I was and very controlling and jealous, he was also very mentally abusive and he ended up having an affair. We divorced when I was 19. Shortly after we divorced he took a job working overseas on off shore rigs and did that for 35-49 years. The kept him away for a month and back a month for all of those years so he only saw the girls his month back and then it was at his convenience, he didn’t let it interfere with his social life. He always paid his child support though, never missed and was only late one time. He ended up getting married when the girls were young and encouraged the girls to call her mom. I just said I didn’t want them calling her Mom in front of me. I don’t know if I was right or wrong, I was a very young Mom and I always wanted to do the right thing but I am far from perfect. I don’t always know what the right thing is. I always thought as long as my kids know how much I love them we will make it through the rest. The stepmom and I had issues off and on but I tried hard to get along with her for the sake of the girls. I invited the 2 of them over for supper one night for the girls and just tried to do the right thing. Most people would say they couldn’t believe how well I got along with her and that they would never be able to do what I do. I remarried and had a boy, before they married and ended up divorced because he would never come home he was always out drinking. He however didn’t pay his child support and didn’t spend time with his son which was so heart breaking. I begged him to be a father and it never happened. My son would see the girls Dad come and pick them up and bring them back and it would break his heart, he finally one day asked their Dad if he could go too. Their Dad told him he could go the next time and he was all excited. He was 3 or 4, I can’t remember for sure but he was a bed wetter, we were seeing urologist and trying to get it resolved, but he had a very small bladder. When the girls Dad came to get them he was in a bad mood and I asked him what was wrong and he said his wife was mad because he was letting my son go. I told him if it was going to cause trouble not to take but he insisted. The next day he called mad and said he was bringing him home cause he peed the bed. I had told him that he was a bed wetter before he went. When he got home he had handprints on his little butt. Needless to say I was very upset. When he brought the girls home they were all upset and said that his wife wouldn’t talk to my son or have anything to do with him. They said he asked for a drink of water and she just looked at him and walked off. They were both partial to my oldest daughter and made it very obvious. My younger daughter was very ornery and strong willed but she was still a very beautiful loving child. She did test me a lot, lol but that’s normal. I always called it middle child syndrome. I grew up with a grandmother that didn’t like me, I didn’t live with her but it really affected me and my self esteem. Their treatment really affected her. Anyway I raised these kids by myself, outside of the very small amount of child support he paid he was of no help. I even had asked him to talk to them if we were having issues and he would just say he didn’t want to get involved. He got them when it was convenient for them and if he had a notion to bring them back early I better be there, I guess I was supposed to read his mind. If he was mad at me he wouldn’t allow them to call me or me to call them when he had them. When his wife took him to the airport or picked him up for his job she would not allow them to go with her, she didn’t want to share his attention. When my oldest was 18 she was pregnant, my kids were taised proliferate, we don’t kill babies, God puts them there for a reason. Her Dad tried to talk her into an abortion. Of course I was furious!! She had a precious baby boy, dumped the biological Dad, he was worthless and actually met her husband a few months later. He is my grandson’s Dad in every way except blood. That grandson is now 26 years old and 6’5” tall and I can’t imagine life without him. My girls are 44 and 45 years old now. I have 7 grandkids, 6 of them are from my girls. I also have 2 greatgrandkids that are twin boys and 2 years old. His wife has overstepped off and on, mostly on throughout the years but I have tolerated it. Well it is getting much worse. My daughter and son-in-law and I had some major issues. I suffer from depression and anxiety and I went through empty nest really bad and I made a lot of mistakes. I won’t deny it. I got my feelings hurt very easily. My daughters and I used to be extremely close. I would sleep the top bunk with my 2 little granddaughters or my grandson or they would come and stay with me same with my other daughters kids. They needed me or wanted me I was there. My daughter called and said they needed me I jumped in the car and was there. Well when my son in law got mad at me I wasn’t allowed in the home. He went too years not talking to me or having anything to do with me. I kept hearing from the grandkids that their mom was bad mouthing me and I am pretty sure she did it to my other daughters kids. We moved too much when they were growing up, I didn’t do this. I should have done that, they never heard anything good. Now they compare me to the stepmom all the time, they go over to their house all the time and spend time with them and they have been to my maybe 3 times in 2 years. I live closer than their Dad. When my granddaughter had her twins, I wasn’t allowed to go see them until they decided it was okay, and they were born at the beginning of Covid so I tried to be understanding although I am a nurse. One day I saw their Dad and his wife and I had a feeling they had been allowed to see the babies so I just asked her, have you got to see the babies and she said yes, then it was like oops, she wasn’t supposed to tell me. About a week later my daughter asked me if I wanted to go see them. On the way she made a point to talk about when her dad and stepmom saw them because her stepmom told her that she let it slip. I just acted like it was no big deal, trying to keep the peace. Well I have hardly got to see them in their 2 years. They have never been to my home. I started working as a travel nurse and worked in Iowa for 4 1/2 months, my granddaughter graduated from college and I drove almost 700 miles to come home for her graduation party, which my daughter and her stepmom planned. The whole time I was home 1 week I got to see them one time at that party and they made no effort to spend any other time with me. When I finished in Iowa I requested my next contract to be as close to how as possible, I want so badly to bond with my great grand babies. It’s a 300 mile drive for me to come hone and I try to make it home at least every other weekend. This weekend was the twins 2 nd birthday party. Yes, stepmom/grandma is right in the middle of everything. Thinks she can boss me around. The boys won’t hardly come to me because they hardly know me, I have tried to go see them but there is always an excuse whey they won’t be there. Way back when they were still babies I offered to keep them when she went to class and my daughter told me I couldn’t handle them, I am a 34 year seasoned nurse that has taken care of gobs of kids and was a private nurse to a very fragile baby boy after I saved his life and she says I can’t handle them. When I went with her to see them the first time she kept telling me I wasn’t holding them right, I wasn’t feeding them right, I didn’t change their diaper right. I couldn’t do anything right. I am always wrong no matter what I say and I have gotten to the point that I am so uncomfortable and feel so inadequate when I am around them, my own daughter, who I would walk through fire for. I just am so distressed over all of this. I don’t know how to handle it, what is the right thing to do. She also started comparing my son with her other little brother and my daughter in law with her other little brothers wife, always make them out to be better than my son and his wife. Her other little brother also has kids and now she is starting to do the same thing with my son’s little boy. It’s so unfair. Help!!! Tell me what I am doing wrong or how you all would handle this situation, it is way too much drama for me and now I have gotten to the point that I really resent their stepmom! I’m sorry for writing a book but I am beside myself, I don’t know what to do, I want to do what is right. I don’t want to make things worse. Thank you again for listening.