It sounds like you are in the anger stage of grief. This is good you need to let this all out. It is great that you are finally realizing that this person treated you so badly and that he does not deserve you. This is important now, now you need to focus on yourself and you need to forget all about that A-hole. Trust me you don't need people like that in your life when you can find a different partner that will truly care about you and your feelings.

I suggest that you completely block off that person from your life and start with the healing process. It might take a while and it will hurt but you will be better off at the end of it. Remember this moment and this pain you are feeling right now and use it as motivation to improve on yourself. It may sound cheesy or cringy but it's true, a lot of success and personal gain it life comes from hardships and heart breaks.