Just a little back story ..
I (33 F) met my fiancé (40 M) almost 4 years ago. He has 2 children from a previous marriage and his ex wife has since decided she wants nothing to do with their children. So I took on the role as their mother full time and stay home with them while he works. I have tried to find a job while they're in school and work from home positions but nothing has really worked with the schedule of the children. So I am a full time stay at home mom to his children ( now 9 and 13 was 5 and 9 when we met).
I love his children like they are my own and I love taking care of them and being their mom.
My reason for posting is my relationship with their father (my fiancé) is not doing well. After meeting him in 2021 I had to do a lot of work on helping him heal from his abusive ex wife and his narcissistic mother. He was a damaged man and I felt I could help him. I will say he's come a long way in those almost 4 years. But one thing he can't seem to get over is when I say no to him. If I say I'm really tired, have a migraine(I have an illness that causes these and I am on meds), or sore (I am almost 400 lbs and have some issues with hips and ankles) or just don't feel like it then he throws a fit, gets angry, and treats the kids and I terribly for the rest of the day/night/week. He will snap at anyone who speaks to him, he screams at us for things that are not worth the reaction (example: someone moved something he left laying around).
I have tried so many things to try and get us past this but I feel as though im the only one doing the work. I have tried scheduling sex and sticking to it even when I'm sick/tired/sore. We made an agreement that we would have sex on the weekend because he works 12-14 hr days and comes home and wants sex then passes out on the couch which made it more of a chore for me. That didn't work because he would just treat the kids and I terrible for the entire week then come home on Friday night acting sweet then demanding sex. Eventually l told him that it isn't working for me either because I started dreading the weekends because I was expected to run to the bedroom whenever he wanted sex and we had no family time together because the weekends were only for sex in his eyes. I've cried so many tears begging for him to change this behavior and he says he will but never does.
It has got to the point that if I want to do something as a family or with him other than sex that I have found myself making sure to give him sex 3 or 4 days in a row just so I may get to do the things I wanted without a fight (usually it's something with the kids like camping, fishing, swimming, etc.)
My question is.. am I wasting my time trying to fix this? It feels like I only stick around and try to fix it because I love his children and I know if I leave him then I have no rights to them and I know they won't have a good life with him alone. (Considering I have to have sex with him for him to agree to do things with them/us). Is this abuse? Because it feels like it. I need advice on how to move forward in this relationship because I am getting so depressed and rarely go a day without crying in the shower or hiding somewhere crying so the kids don't see how much he hurts me. Please help