I think that even though you don't think you know how to help your friends you can help them anyway. I know what I need most when I feel that way is to be told I am ok and that I am loved. You can't fix them, they have to do that themselves. But you can tell them you care. If the fact that they cut upsets you and makes you angry, let them know that you are not able to cope with it. Those feelings are your problem not theirs so it is up to you to set bounderies by telling them that you can not deal with hearing about that particular part of their troubles though you are there to listen about anything else. By setting those bounderies and making them known things will be emotionally safer all of you. Perhaps when you discuss this with them you could also give them a couple of numbers for counselors or support groups or the crisis line. That way they will have access to someone who IS able to discuss these things with them.
Carrie

<font color=green>Not knowing when the dawn will come, I open every door.--Emily Dickenson