Often times to cut out bad habits/ addictions you need to cut the bad out of your life... It doesn't sound like she is right for you. You obviously want someone more committed and it just doesn't sound like she will be that person for you.

Please don't cut, in the end it only hurts you, and the relief you will get from your feelings are only temporary and those feelings will still be there once the damage is done.

Can you work out your anger and pain in a different way? Go to the gym, a walk or run? I think ultimately if she continues to choose to hurt you, you will have to let her go.