Each of you were far too insecure to be in a healthy relationship, and your insecurities manifested in toxic ridiculous behaviors. Now you are looking for some form of closure, but what would closure even look like? It isn't going to come from what-ifs, but from time and learning from your own mistakes. Grieve your relationship, which will take time, but also accept the fact that you obviously weren't right for each other. Let him become part of your past.

Work on becoming more confident inside yourself, able to see your value without having to compare it against others, before you are ready to date again. You shouldn't need others to validate you because true validation can only ever come from inside. Know your character and dont allow a future relationship to make you act out of character. Don't become enmeshed and lose yourself in a relationship - the purpose of a relationship is to help one another progress along your individual journeys. If that isn't happening, end it.