I am so sorry to say, but my first thought would be since you are ready to talk about it, go to a therapist first. A therapist could help you and your situation more then a priest right now. Please seek professional help.
How does the Catholic Church look down on self harm? How can I talk to a priest about it?
I wouldn't bring the Catholic church into this just yet. Go find yourself a therapist first and then take it from there.