His mother or me...

It's not like, "you need to choose between us" but, my SO has been driving 45mins each way to pick his mom up and drive her to the "doctors" 2 times a week. I just found out I need to go for an emergency visit, with upcoming surgery for me, on one of the days he brings his mom. He won't come with me... In the 2 plus years we've been together, I find myself doing a lot of important things alone... His mother has serious mental issues and is completely fried from the massive amounts of drugs she used while he was growing up. I try to stay away from her as much as possible, I'll be very nice if she asks for something, or is somewhat "normal" but the other night, I was going about my business, on top of dealing with my injuries, and worrying about my upcoming surgery, when she started sending me text after text, being extremely hurtful, saying awful things, and mostly blaming me for her problems. After texting her back "stop" she told me I'm being mean to her, then at 2:30 am, she sent a random picture.. I was so infuriated, I couldn't go back to sleep. He revolves a lot of things around his mother, I can't deal with it, he doesn't talk about marriage, children and I'm getting fed up. He lives with me... And I've told him a couple times already I'm done... He won't leave. I don't know if I really want him to, but I usually think about being better off alone... Help 😔