He's moved on first ?

My ex and I broke up about a month and a half to two months ago after dating for six months. He was my first real boyfriend (I'm 20) and he broke up with me once before and then came back saying he made a mistake so I took him back. We tried to work it out for another month but decided to part ways for the last time. It was pretty mutual but still upsetting. He and I have mutual friends so I'm sure I'll see him again. He also has some of my stuff that I will need to pick up at some point. My friend told me that he's dating again, and I know I shouldn't care if I'm over him, but it still hurts to know that he's so over me.