pinkbride's Pink wedding

Okay, I was wondering if any of you are having this problem too:

My fiance and my mother do not get along. Well, actually, my fiance has been very nice to her, never said anything rude to her and has done a LOT for her. Yet my mother has been very mean to him and has been making things difficult on the both of us. I love her dearly and I know she's very sick. (She was in the hospital for a month when he and I started dating) She has bad stomach problems, throws up every day and faints every day. (The doctors can't really seem to find out what's wrong with her for sure, but she does have IBS)

I know she doesn't want to "lose her baby" (I am the youngest child, I only have one other sibling...my brother who is 26) She doesn't like the fact that I am basically living with him either and I know my grandparents don't agree with it either. (I am Christian and grew up in a very Christian home....but I still want to do this, I don't believe everything my family does) Every time I go there for a week or so and then come back here, she gets very upset and angry and starts insulting him. I hate that!! Today she called him a son of a bitch and then proceeded to insult his family. Whom she hasn't even met. She got mad because my grandmother told her about how I'm going to start getting to know his family and mother better since I didn't have a close relationship with my ex husband's family and we didn't get along. I don't want that to happen this time. I want them to like me and I want to like them!
She is TRYING to make me feel guilty, from all the things she said (I won't say EVERYTHING but ...it was BAD) Sometimes I do feel guilty, I don't think I should! Yet I think about how sick she is and how terrible her life is and I feel just really bad about it all.

Ugh. I don't know what to do.
It's stressing me out and now I'm getting a bit depressed again. (I'm already on Lexapro)

This should be a happy time! I wish she could just be happy for me. She even told me today she doesn't want me to marry him.