As with anything that involves research, life choices, health issues, and healing I wanted to caution, let the buyer beware. I have only included links here that I researched and found to be reputable, mostly from non-profit organizations, or other survivors. Even if something is free of cost, it can still have consequences in your life, both negative and positive, exacting a cost, so let the buyer beware when making any choices, educate yourself. You deserve to get the right help that assists you in healing.
I caution against online therapy, buying books, and giving your money to someone who says they have a treatment for you online. Look for the most reputable resources, you deserve the best and the best healing assistance.
I would recommend educating yourself and acquiring a therapist and/or doctor who are reputable and knowledgeable and sharing with them the specifics of what you are dealing with.
Life With Dermatillomania (Psychology Today)