I'm going to tell my friend that I'm not her personal therapist
What does she tell you?
She tells me all the bad things in her life. The last time I talked to her, she talked about her family problems. That was a long time ago
Friends should listen and provide support to each other.  You are expected to have a give and take relationship in a friendship, they might also enjoy listening to you.
I get that but I'm tired of it. I don't want to be part of her life anymore.
If you feel that way then that's okay. No one should be forced into a relationship they no longer want to be a part of. You should tell her that.