Hey Skwirl, Good for you! It's about time isn't it? Look, the fact of the matter is some people are controlling and it is up to us to draw that line as you are finding out. You are entitled to living your life as fits your needs just as your mother lived hers as it fit her needs.
Guilt trips are another way of controlling and if you ask me, it's a pretty low way to go (been there with my mother). Love doesn't involve purposely controlling and hurting others just so their life can be the way they want it to be. You obviously have hit on a nerve with me because I find it so insulting to be manipulated by someone because of their own selfishness (my mother).
Take care of yourself, your life, your husband. He's right. May I suggest that if it is difficult to transfer your mom that if she wants to get out more to perhaps try dieting to lose some of the weight ...it will be healthier for her and less dangerous for others. You deserve loads of credit and I know how hard it has been for you. be good to yourself.