Just wanted to say thanks for responding, and everyone's help has given me alot to think about.
Yesterday I got another e-mail from the aparents, detailing on how much they've gotten so far. I'm starting to think that (possibly subconsiously) they're trying to pressure me into not being able to back out. Everyone keeps telling me that i'm 'too nice', because I can't even imagine telling these people if I back out, no matter how much I want it...