Sorry you went through that!
How unprofessional of them I would certainly write a letter to complain about the way they treated you and how you overheard them acting like a bunch of idiotic highschoolers, people like that should not become DRs!!!
I can't wear all kinds of stuff due to scars left over from my bad acne years and my hairy arms. It does make shopping hellish at times, especially looking for summer clothes.
The only thing that stopped my cystic acne was accutane, I think some cysters have had success with spiro (I've never tried it myself though).
Best of luck, hope you find something that works for you and a better derm dr!