My friend back stabbed me =(?

Tell her how you feel, if you don't know you never will... Make her feel bad, but in the future try writing down your negative feelings about someone in a journal and either throw it out or hide it. It feels good to get it out. You should forgive her but tell her what she did was wrong and tell her that you never should have said anything bad about Jenn in the first place but a secret is meant to be kept.