Feeling 'required' to take care of my granddaughter

you have o stand up for yourself.
it is not his place to order you around.
you sound like you are trying to justify why you should be excused; that is the wrong approach. that is giving him the power, like an employer whom you are begging something from.
don't discuss, don't explain.
simply state. and repeat as necessary.
broken record method.
read up on assertive communication.
see dr les carter on youtube.
good luck.

Your time is your own babs and if you are working hard weekends are very precious and necessary to recharge. Maybe say that to your son ? I would try to come to a compromise and perhaps every other week or whatever is comfortable for you, not him. Don’t let him brow beat you because that is just unfair on all of you.

My son has a way of going on and on and on and his wife did not intervene when he was talking to me. Her mom does not work, never has, and lives in Europe where I think things are different. She would have loved to have been here during the last year to help but she can't. Yes, my husband knows because I called him where he is up camping at our place and I was nearly in tears. He knows exactly how our son is. I know he will say something to him which will just make things uncomfortable. So why doesn't my son ask my husband to take her for a couple hours on the weekend? Because I'm 'mom'. My son as a way of laying guilt trips on people that I don't like. This is not the first time he's done this to me and I know if I didn't work he would want me to babysit for full days which I would never do They are talking about having a third child. I am pushing back against that because I know that would just make things worse. My son did sound surprised at the fact the 2 year old behaves perfectly for me because she really does but then that's what grandma's are for. She and her mom have a lot of problems and I think there's a lot of burnout going on there. 2 years old going on 12...... They are looking into preschool this fall to give everyone a break from each other.

Your time is your own to do with as you wish. Me? I would jump at the chance to have my GC but that's a different matter and I currently have more time to do so than you seem to. Is there room for compromise here? Could you perhaps have GD every other weekend? Find the fact that son 'insists' somewhat uncomfortable. I would make myself unavailable now and again by arranging a different appointment or even staying away from home now and again so that I was physically unavailable but that's me. I think you have to nip this in the bud or it will quickly become the norm. Your son sounds a little bit controlling but I've maybe read too much into your words. Presumably your husband is aware of this situation? Perhaps he could intervene. Good luck.