You're definitely not alone.
I get nasty blocked pores on my shoulders and upper arms, and I started to pick at and pop them when I was stressed, and have an assortment of nasty scars to show for it (they do fade in time though).
I guess it's a compulsive habit - there's something so satisfying about getting the lump of yuck out that I went into a calm, almost trancey, state while I was doing it.
If there's something else that can give you the same calmness, try displacing with that instead. I found I used to mostly pick on the loo (because no-one could see me), so kept a really juicy novel in there to distract myself; but stopping for a cup of tea, or getting up and walking round the room, or putting on some handcream or something might work too.
One thing that worked for a while and was v handy at work was a little essential oil rollerball scent thing from the Body Shop - you put it on pulse points when stressed and the fragrance was meant to calm you down. When I found myself going for the shoulder I'd divert to the desk drawer for the scent thingy instead. Even if the aromatherapy was all tosh, just doing something to break the cycle was helpful.
I also found that having a target helped a bit ie if I knew I was going to have to wear a strappy top for a party or something I'd try to stop picking for two weeks beforehand to help them heal - I'd let myself pick one really good one a day, and no more, and that actually worked quite well to drag me through the really bad patches.
The other thing that really helped was that DH is very skin conscious as he had bad acne as a teenager that left his back scarred, so he had spotted it was a problem for me and wasn't afraid to talk about it and be supportive. It does sometimes make me cross when he says 'stop picking!', but both of us are aware that I use it as a calming mechanism so I'm cross that my comfort blanket is being taken away rather than actually cross at DH.
When my shoulders were looking better (eg at party after two weeks of rationed picking), he'd always say how lovely I looked, and now they're clearing up altogether he often makes a point of how nice they're looking now. Sounds cheesey I know but we do do a lot of supporting each other - he needs the same kind of recognition when he loses weight.
It did all work - kind of - and I'm now happy wearing strappy stuff (unless I get a big red spot, but that's another issue).
You will get through it - feel free to try any or all of the above ideas, or CAT me if you'd rather.