Forming healthy relationships

I’ve been working on my self this year. I dropped a lot of friends who I only ever drank or smoked pot with and I’m doing the best I’ve ever done in school and I’m proud of that.

My girlfriend left me recently and I always knew she was my entire social life and best friend; I never minded until now that she’s gone. It feels like I have nobody left I can relate to.

I feel I don’t know how to form relationships or communicate. I go to social events I exchange information I communicate well enough in person but I never know what to say or how to initiate plans, or what to even do if I made plans.

I have ADHD and when I was younger I really struggled with becoming super fixated on people and this often pushed them away, made me come across weird and I’ve built this wall around myself.

Another issue is socializing with people for me used to be smoking pot or drinking; I don’t want to fall back into that and just as I meet people I could hang out with, it seems like they only wanna smoke or drink.

How do friends communicate with one another? What do healthy people do for fun?