Unhappy relationship or single parenting with RA

I developed RA straight after having my first child. Despite struggling with this I still did all the night feeds and even found myself stuck in bed with the baby or crying in the floor. I got up with my second child and dragged both down the stairs on my bum. My partner has osteo in his one knee and works. I developed a deep resentment and since then things have improved.. sort of. I do now work full time. My partner doesn’t drive, he started learning three times but has given up. We have wasted so much money. Despite my ra still not fully controlled that means a lot is on me. He does his share of the house work yet still 80% of the time I feel like a single mum. I feel trapped, iv always been so strong and fit and I’m scared if I ask him to leave my kids will suffer even more. What if I can’t get out of bed one day? Will it be too much of a burden for them as they get older. On the other hand, I think despite it all I am the one who gets the out, takes them to parties and decorates. As I right this I know I’m probably no worse off single but I can’t help but worry.