So what would you do?!

Okay so you have this friend who is always putting herself down, and you are trying to build her up. Well she is always saying how fat she is and everything.. Then all of the sudden she is attacking you. Calling you fat in front of the guy you like and all your other friends. Like what should i say to her... i mean i know she goes though alot at home and everyone is really tough on her. I really dont want to hurt her to ya know

Sometimes actions can speak more than words...
Embrace her and let her know it hurts you that she, such a beautiful person, thinks of herself that way. Let her know that even though she really hurt you, you will still try to be there for her when she needs help.