Single for two years feeing hopeless.

Hey guys I’m a 21f and have been single for two years, I was in a long term relationship from 15-19 and it ended in him cheating with his ex out of nowhere. I know it seems dumb but I can’t put myself back out there I feel so hopeless I don’t want to go through that again and I don’t know how to start finding someone new. All of my friends are in relationships and I just feel alone any advice? Thanks.