Wedded Bliss...?

About a week or two ago I got the invite for my so called friend's wedding. Since then it's just sat there and the wedding is on Halloween. I know, it doesn't sound too good considering this is supposed to be my best friend and we've been close since we were 12 but after all that's happened with her the last couple of years I'm not sure I really want to go. The whole thing is a REALLY LONG story but to make it short she's shown me that she's really not a friend at all and well, I don't really care to talk to her anymore. This creates just a bit of a dilemma. It would look horrible if I don't go but how can I go when (and this is gonna sound bad) I just don't care?! She certainly didn't care when she informed me that she was getting married and that I was invited as long as my DH didn't go...she didn't care when I took the time to call her since she didn't call me and so rudely held conversations with whom ever was in the room with her while I was talking...she didn't care when I told her that my DH had been stabbed (not even asking if he was still alive)...and that's just within the last 6 months!

I really should send the r.s.v.p. card in but which box do I check? I think the biggest reason why I don't want to go is because she ended up inviting my whole family including DH but I know it was only because she thought I might not go otherwise. How can I show up and be "happy" when I know that the situation is bad to begin with? Normally I don't have any problem sucking it up and being the bigger person but this time I think I'm allowed to be me for once and put my feelings first. What would you do?