How to focus on myself?

This past year guy after guy has used me and wasted my time. I’m so tired of it I want to focus on myself, I deleted tinder and those types of apps cuz I really want to focus on myself and school, I don’t want to be caught up in any more bs. I’m just finding it kind of hard, I was recently talking to someone and he made it seem like he really liked me but out of nowhere he told me he was getting back with his ex for the 5th time! Part of me feels sad looking back at how I’ve been treated but I really just want to move on, I just need some ideas as to what to do to keep my mind off these things