It is normal to be angry or revengeful after a breakup. I think the reason your feelings are back again if maybe because you didn’t get over her the first time. There’s a whole sequence of feelings that a human being feels after heartbreak. Reading this article helped me understand my emotions after breakup better:

https://nowandme.com/blog/neuroscience-of-broken-hearts

All I can say is, you have to give yourself time to feel the pain of your breakup so that you can get over it completely. You have to allow yourself to be sad and angry for a few days or even weeks maybe. And then you have to know when to put a stop when you are done. It is like grieving the death of a loved one. You have to process that grief. The same way you have to let your heart understand what has happened by allowing it to be sad. And then work toward feeling better.