Distraction and happy things is what worked for me. I love music, so music was my way of keeping my mind occupied with something else. Or even to feel again,because I know the numbness you mentionned.
I'm also in this vicious circle right now. I stopped cutting because I got annoyed by the scars too. What I do instead is not healthier. Bruising. Also visible marks but not forever. BUT: All of this is completely bad and none of this helps with the real problems. It's working good as a coping mechanism,I know. But it doesn't solve any of the underlying problems. Are you in therapy?My advise: You should get professional help. That's one thing to improve your situation. Hope you'll be better soon! If you feel like talking: I'm here for you.