new to the forum - my girlfriend is a picker...

Hey everyone! I'm Sevel, you can also call me Red. I have been with my girlfriend for 8 years now, and friends for longer than that. We are both 23 years old and living together while going to school. My girlfriend has picked herself ever since she hit puberty, and started picking me about 5 years ago. I didn't worry about it much at first but it's gotten completely and totally out of hand! She goes nuts picking herself, especially when she's stressed, and will sometimes lock herself in the bathroom and pick for up to two hours. I don't know if her arms will ever heal, they are always covered in dark red wounds. I have to fetch her from the bathroom all the time. She says she doesn't even realize she's doing it until hours have passed. And she when she's not picking herself, she picks at me! Whenever we are relaxing together, talking, laying around, she instantly is gliding her hands over my arms or back, looking for skin to pick. If I let her she would leave me completely raw. I didn't worry about it so much at first, as it was just once in a while, but it is every single night now. When I try to stop her she will get extremely frustrated and upset and will sometimes lightly hit me in annoyance. She's tried to stop before, but it's never lasted more than a week. Creams don't help, wrapping up her arms doesn't help as she'll peel them off and pick beneath them when nobody's looking. She is on medicine for her anxiety disorder and chronic depression, which is helping her - she spent a week at the hospital last year due to severe depression - and while she is happier and better at coping now, she still picks just as bad as ever before. What worked for you guys? What helps you stop picking yourself? What should I do???