Am I depressed?

I was with this guy for a few months and it wasn’t anything serious until recently. In July I went on a trip to Europe without him for a month. The week I got back I found out that he cheated on me while I was away (I was with him when I found out, and no, he did not tell me himself). I broke up with him immediately and honestly felt fine, I was actually shocked that I wasn’t affected by it at all. A few hours later that same day I felt a little sad but I forgot about it right away. I didn’t think about for a week or two but now it’s all I can think about and I’ve been home alone a lot and I just feel sad and mad all the time and can’t stop thinking about him no matter how hard I try. I can’t help but blame myself every once in a while, but I know I shouldn’t do that. Is it normal that its been over a month later and it still feels like we JUST broke up?