Bestfriends are fighting, annoying me a LOT?

Okay heres the situation: there is one guy friend and one girl friend of mine. They went out for 6 months. They've both had depression issues. They are now continuing to fight after a month of being broken up. Reason for break up: guy friend cheated on her (not physically but emotionally). He told me recently he did it because she has issues a lot and the stuff she put him through was too much for him. He started to hurt himself. He couldn't take it so he cheated on her (as described above). She hates him now and wants to hurt him as bad as he did her & he just doesn't want to be around her anymore. I'm caught in the middle and its like frickin tug-of-war and I can't take it anymore. Stupid high school drama I need help with. Any suggestions or comments on this?