How Do You Deal With A Toxic Friend?

So, I have a friend with whom I have a very odd relationship. She tends to only contact me whenever drama in her life seems to pop up and then, she unloads on me… and gets mad when I unload on her and then she claims I don’t appreciate her.

Recently, I’ve reached the end of my rope and I am not sure what to do with her. So, my mother died recently and while I got calls, emails, blog messages, facebook messages, etc, etc, from just about everyone else… except this one girl. She didn’t say a thing to me and I brushed it off until last week when she contacts me out of the blue to tell me that she’s leaving her fiance and this and that and I am thinking, “Wait, WHAT?”

Okay, so now I am not sure if I should cut her off or try to explain things to her. What do you guys think I should do?