TW: break up, hard feelings, compulsion, etc.

I'm sure that many people here pass at least. I'm going through a moment that I can't control these things:

1. I'm focusing only on the good things that happened in the relationship and forgetting the reasons why we broke up (the relationship became toxic and painful for both of us, although I was the most affected, emotionally);

2. I can't stop thinking about how he is now: is he happy or sad? Is he looking for other people already? Miss me? Is he's gonna get into another relationship first than me? What if he finds someone better than me? 

3. I'm fighting my impulsiveness. I want to focus on myself, but I keep looking for men with the potential to be my next boyfriend or FP. I don't want it. I've been looking for someone, for being in love since I was 13. Like, I'm so tired of that. I feel exhausted when I do that, but I can't stop. 

4. All the things I mentioned is making me tired, sad and so empty. I really need a way to get out of this, but the thought of being alone is killing me. 

Does someone know how to help? I really need some advice.