UPDATE:

So the difference between my situation and the op situation is that my gf is a total bitch. She's also my first "real" girlfriend and I let myself get way to attatched to her. I could go into detail about all the horrible things I've had to put up with but it'd take an eternity. I've very confident she's bipolar, but won't call a psychologist, and is terrible to me. So I'm giving up on her. I've let it affect me and my friends way to much and I'm sick of it.

Here's the real dilemma. Her mother is psycho as well, but loves the shit out of me cuz knows her daughter is psycho but I put up with it. So she's taking me and her to puerto rico for a week.... in about two weeks.

She is in fact so crazy that she's about to break up with me just for trying to explain why I should be able to go. After 15 months of dating....

So question is, do ethically, do I deserve to milk this vacation and try and deal with this shit or should I do the right thing and end it now.

EDIT: GF has cheated on me before twice with the same guy although not passed first base. I can gamble and drink in puerto.