Here are a couple of blog posts from the Biblical Counseling Coalition website that have some helpful thoughts on cutting:
Cutting: Bleeding the Pain Away
2 Lies That Must Be Defeated to Overcome Cutting
This second post is the first part in a multi-part series that doesn’t seem to be up yet. Both articles do a great job of pointing towards Christ as the only true remedy:
“The alienation you’ve felt from your parents, your peers, your teachers, your bosses, and God has a remedy. The blood of Jesus purifies us and opens the door for good relationships with one another. So trust in the blood of Christ, not your own blood. Blood is very powerful—when it’s Christ’s blood!”
Irrigating Deserts 