How can I tell my mom that I want to talk to a therapist?

I really think it would help me but we can't afford it. Does insurance cover it? My mom has never seen what I've done to myself. She knows how emotional and serious I can get and she worries about me all the time, but I'm scared to show her my imperfect side. I don't want to tell her what I've done until I'm ready, but I want to talk to a psychiatrist or somebody besides the school counselor, someone that no one at school would know I'm seeing. How could I tell my mom?