I cut my wrist for awhile, and I understand when you say that it comforts you. It's weird, but when you're upset or angry or whatever, you make one cut, and it's like a weight is lifted off your shoulders.
My sister saw my scars, and it hurt me to no end. I realized after that, that self-harm is not the way to go. The only thing you're hurting is yourself. You should definitely go see a therapist, or try snapping a rubberband on your wrist when you feel the urge to cut. That's what I did.. I hope things get better for you. <3