I don’t know how to be happy

I broke up with my on/off boyfriend of three years officially about a month ago… I loved him but soooo many things played a part of us breaking up. It was to the point where I was basically a therapist/mother to him cause his family sheltered him to the point of no return (he barely did anything for himself) and it made me resent him a bit. Which cause some issues for myself…. I didn’t want to leave because I thought I was the only thing keeping him together (that’s how bad it was) During the times we were off I hung out with a friend from from college and I regretfully began to have some feelings for him. I wanted to officially end it with my guy cause I didn’t think it was fair and we agreed as we thought it would give it time to work on ourselves (we’re still friends) but I get the feeling that the other guy likes me and even if I wanted to date again (not anytime soon) I feel so hopeless like I don’t know if we’ll even be a good match or if I’m even good enough. I still cry sometimes cause I feel like I failed and ruined my last relationship. I don’t know how to handle a relationship anymore especially because I don’t to burden anyone with my issues either… I feel like it’s best to be alone so I don’t hurt anyone again.