((((_embrace)))))
Good for you for signing up for that type of class! That takes a lot of sheer will power to do.
About your question - you can either hope he doesn't see them, or how about wearing long sleeves? I know here in Ontario that the weather is getting a bit colder day-to-day so I'm assuming it might start being colder on the East coast soon? Makeup might work too. Personally, I'd try to hide it with sleeves, and if it was noticed to talk to them about it. They can help and might be able to suggest a therapist who would be able to help you stop self-harming or give you other coping mechanisms.
((((hugs)))) Take care of yourself and PM me anytime.