Im shy around a group of certain people, i really want to change but i need someones help..plz answer?

You know when your a little kid and you look up to the big kids that you think are cool? well in my case I tried to fit in by doing drugs with them and everything but i was always really shy around them growing up....well now i quit everything and my brother throws beerpong every once in a while and the drugies comeover..well because of my past whenever thay're over i get shy again and i think so little of myself..almost like ill get dirty looks from them if I be myself...i realized that they are just low lifes and i dont care if they dont like me at the end of the day, yet im still super shy around them! any advice?