I wish you the best, but in my experience, things don't really ever get better. Throughout our 20 year marriage, they never accepted me, although they did admit on several occasions that I was more of a "mom" to them than their bio mom. That admission always was followed with an extended period of rage toward me, I suppose because they felt they were being disloyal to their mother.
The kids' never-ending anger and their father's constant attempts to win their love (even at my expense) took a huge toll on our marriage. We divorced after his kids turned their backs on him (his choice). Due to some legal issues, I had to stay in touch with him, however, and I even moved to the town where he lived at his request -- not because I couldn't "live without him," but rather, to keep an eye on him so he would not leave me on the hook for some debts he had run up with a business that failed. As soon as that issue was resolved, I discussed our relationship seriously with him and we both agreed that there was no love left. I started making plans to move to another state when he was diagnosed with a very aggressive cancer and not given long to live. As much as I wanted to leave, I felt I had to stay and take care of him in the little time he had left. I asked him if he wanted me to contact his children since they didn't even know where he was at the time. He emphatically said no. That he'd had it with them and their selfishness and greed. I even asked hospice to talk with him about it without me present, thinking that perhaps he was just trying to appease me and keep me there to care for him. He said the same to them.
After he died, I found out that he had a will drawn up, leaving everything he had to me (what little there was) and being very specific about how he did not want to leave anything to his kids.
And so life went on. Then 12 years later (this year), I suffered a cardiac arrest. Luckily, I was in the hospital at the time this occurred, but there were complications. I had to have open-heart surgery to replace a prosthetic aortic valve and I had a bacterial and fungal infection of the heart (endocarditis). The doctors went on the search for next of kin. My neighbor, who works for the police department, found two of my stepkids living fairly closeby and contacted them. When the doctors asked them if they wanted to put me on a ventilator (I stopped breathing every time they tried to take me off life support) or just pull the plug and let me die. From what I have been told, my stepdaughter was leaning toward just pulling the plug because she thought I would be mad about the scar left from having a trach (for the record, there is none). The oldest stepson was clear from the first time my neighbor contacted him -- "I don't care if she dies," he told her. "If she hadn't married my father, I could have had a Corvette." BTW, he's now in his 60s and has a very good job as does his partner. It's very muddy, but it appears that the only one who favored trying to save me was the middle son -- the one I'd actually had the worst relationship with.
And so I was put on a ventilator and spent the next five months in an acute care and rehab hospital. All the while, my neighbor who found the kids was laying guilt trips on me because I did not want to see them. I knew that I would eventually have to talk to them, but at that time, I was still fighting for my life and simply did not have the energy to deal with them.
So eventually, I got out of the hospital with only seeing the two that live close one time, a few days before I was released. The girl came to see me a couple of times after I got home, but it was obvious that the reason she there was to try to get me to give her my baby-grand piano. The middle boy (not really a boy now -- he's in his early 50s) started coming to mow my lawn and do some odd jobs once a week. He pressured me quite a bit to give him power of authority over my finances and medical decisions. He also was very interested in knowing if I was collecting on his father's social security and other things. He told me that I should not trust his sister or brother because while I was in the hospital, all they could talk about was what they wanted when I died. I totally believe this. I also believe that the middle son was a party to this discussion as well, although he tries to make himself sound innocent. These kids were obsessed with what they were going to get when their father died from the very beginning of my relationship, saying things like, "Dad, when you die, can I have your stereo?" out of the blue.
The kids never accepted me as their father's wife and therefore, they believe that everything he and I bought should now be given to them now that he's gone. They even think that things like the piano, which was mine before we married, now should be given to them.
The girl has stopped communicating with me and her brother (the middle son) is annoyed with her about something. I suspect she has complained to him about me not giving her my piano.
The oldest son was all sweetie pie to me on the phone when we talked, making it sound like he was so concerned about me when I was ill and saying all he could think about was how much he wanted me to get well. Obviously, he doesn't think my neighbor told me what he really said and how he really acted.
The middle son seems sincere, but I don't trust him either. He was the most threatening toward me when he was younger and I know how skillful he is at presenting himself as someone he is not. I'm giving him the benefit of hope that he has changed, as he says he has, but every now and then, I spot little things that tell me things may not be all they appear to be on the surface.
At this point, I recognize that I'm getting older and have health issues that may land me in the hospital again. I'm not comfortable having any of my stepchildren in charge of my finances and medical, so I'm going to make an effort in 2020 to make more friends and maybe even get married again. I'm also going to make sure I have my affairs in order and my wishes are known to someone trustworthy.
It's not a pleasant thing to have to consider, but when you have stepkids, you need to be realistic about what the situation is and isn't.
By the way, regarding your stepson moving back in with you, we had a similar problem with my husband's oldest son. He was very belligerent toward me, telling me to throw his trash away for him if I didn't like him throwing it on the floor, parking in the garage and telling me to park on the street, etc. When he bought an expensive sound system instead of getting place of his own, saying that since he wasn't paying rent or food, he was going to take advantage of the situation and get all of the "good stuff" he wanted, I came up with a plan to get him to move out. All of the kids are very picky about their food. This one, in particular, claimed that he was allergic to anything he didn't like, like tomatoes, cucumbers, mushrooms, etc. So I started making dishes that had these items in abundance and when he would complain, I'd apologize profusely and say I had forgotten about his allergies, then recommend that he go fix himself a bologna sandwich. He moved out a week after I started doing this. Good luck!