Is it bad I'm glad my ex broke up?

So my first boyfriend cheated on me multiple times and one day I couldn't stand it anymore and broke up with him. This was over a year ago.

I was really pissed off when he started openly dating the girl he was cheating on me with, and thought it was unfair.

Over the year I have accepted it, moved on, and mostly forgotten about my ex. I just found out today they broke up. Why does this make me happy? Is it bad that this made me glad?

Maybe it's because she was the girl he cheated on me with and she knew about me that made me hate them.

Maybe it's my little revenge thought that I have?

I think now I couldn't care less who he's with though. I just hope it doesn't mean I'm not over my ex because I'm glad with this situation