Tell your T about it.
I had similar situation but my T knew about it, then I started to think that he cant love me because Im sick and then I tried to stop it to make him like me. Maybe it sounds horrible but it helped me and motivated me to stop it but it took long time period because I was cutting for 3-4 years and now Im not doing it anymore, sometimes I think about it but I dont let myself to do it.
Im also borderline and was really out of my mind.