Depression

My bestfriends has had depression for a while because her mom is very sick, and her dad is cheating on her mom. Today she had a fight with her boyfriend (who is also depressed) and she cut herself pretty badly. I took her to the guidance counsellor at my school and she told them everything. I know she is going to start getting better because our school is very supportive. But I know half the problem is her boyfriend, they've been together a year and love eachother, but he is definitely making everything worse for her because he just gets frustrated and takes it out on her. There is no physical abuse, and when they are good, they're great together and so happy. It hurts me so much to see her this way. I know she should break up with him, but she's afraid he might commit suicide or do something drastic if they break up! What do I do to help her?! I really don't know what else I can do but I feel like I should be doing more.