Friends

Ok so here's my problem. I babysit for a friend almost every tuesady. And the thing is that we haven't really been friends since she got pregnant. I just haven't been gutsy enough to tell her I don't really feel like we are friends. We have nothing in common with eachother anymore, and to me it seems like she is only my friend so she can use me as a babysitter. She bugs the hell out of me and assumes I want to spent the entire day with her instead of living my life the way I want. She is always signing me up to do things with her, and I am sick of it. Everytime I come up with an excuse not to hang out she comes up with a way around it, and I can't think of another way out. Every week I get sick trying to tell her a way out of it. But never, I never get out of it.I just don't have the heart to tell her I want to end our friendship.