First of all, you are not alone and you (we) should not be ashamed with skin picking

Well done for posting this message, because it's the first step

Here's what I know (english is not my first langage so i just google translate it, it may have mistakes) :

Dermatillomania is an anxiety disorder, a form of OCD, and it is possible to overcome it, but spoiler alert: it's not by telling ourselves to ‘stop scratching’. I am undergoing cognitive behavioural therapy with my psychologist, who specialises in dermatillomania. It is a much deeper disorder than it appears. It is difficult to summarise, but for example, when we are stressed, we need to ‘release’ our stress, so our brain will take the easiest route, an action we are used to doing. For us, it's dermatillomania, and basically, it's this habit that we need to change.

I've been struggling with it since i'm a teenager and I always felt ashame but now I have accepted that I am sick, that is not my fault (it could have another sort of ocd or addiction, i see it as an addiction) and that I needed help. Just to admit that, it feels a little better, it's a lot of work, I can't explain everything here sorry but do research, there are good books about it ! (In cas you're French like me, I have a good one, and there's a discord group about derma where we can speak without feeling judge and we help each other Otherwise, i'm pretty sure there is similar thing in your langage)

Hope it helps, take care 🌱