I'm sick of my girlfriend?

I need to get out of this sham of a relationship. She whines about everything and I just don't care. She doesn't like the gifts i give her, my car, my parents, my house, my friends, my dog, my hamster, the food i make for her. she says they suck and are stupid and that everything she has and does for me is better. i've already cheated on her a few times and she knows but she still thinks i'm in love with her, i need to end this thing but i have tried in the past and somehow we stay together i have ed her for her whining before but she doesn't get any better? should i break up with her or is there some way she could become an okay person, because we had a really good year of dating but the last six months has been total hell. please help!!!