Just got out of a 2.5 year relationship, don't know what to do

I recently got out of a 2 and a half year relationship with a girl who I know full well was bad for me. She was 13 when we got together and I was 16 (16 and 18 now respectively). She cheated on me twice and was generally just really shitty to me and used me to get her way. I think because of the age difference I was way more willing to conform to her.

But we broke up on the 10th of November and since the 13th she's been with one of my best friends (Who's around her age) and that's really put a downer on me.

The problem is, I really don't know what to do, I don't know how to meet new girls, I can talk to them entirely fine but I am completely stumped when it comes from how to change it from talking to seeing if they're interested. Any help Reddit?