I scratch my hands when I'm nervous -- I have hand eczema (and elsewhere on my body, but my hands take the biggest beating). You can tell when I am extremely stressed because my hands are bandaged up. I've gouged myself rather badly, not realizing until I notice all the blood under my nails. You're not alone!

I have talked to T about it a little, but mostly if I notice it I will sit on my hands, which I often have to do in other stressful situations, like when I am making small talk with a stranger. My H will tell me when I'm doing it, and at tough times I have asked close friends to also alert me if I start scratching in front of them. Perhaps you could do the same with T? It's one way to open up the topic. "Hey, I am scratching myself up pretty bad; can you help me by bringing it to my attention when I start doing it?". I am considering doing something similar with my T.

Good luck!