How to stop playing a song in your head on repeat

I have this specific song I keep playing in my head. It feels nostalgic to me and reminds me on my ex and how ugly I caused her to break up with me and how sad I am.

This won’t go not even 6 months after the breakup… it was my first relationship (i am 24) and i feel shit and now this song in my head makes me feel so nostalgic and sadder.