If its leaving you in such a mess, don't go. If you want to someone to tell you what to do, then all you need to read is this: don't go. Make up an excuse if you like, but you can simply say, thanks but no thanks.

It is very hard and your feelings are very legitimate, but why would you keep going to people who don't care about you? I'm sorry, family may be family, but sometimes in name only. Like a previous poster said, it seems you've already made up your mind about how you're going to feel so why make it so hard for yourself.