So sick of obsessive thoughts...

I get an obsessive and intrusive thought in my head everyday which is a real memory of being bullied by a friend. This friend tried to test whether I understood a puzzle and when I got confused and anxious and asked for clarification, she told me I was stupid. I think about it every day. I am interested in hearing people's tried and tested methods of either getting the thought out of your head, or if not, at least making it less distressing. I find the thought distressing because I have equated the memory of being shown the puzzle as being proof that I am stupid. I try to remember the puzzle in order to solve it, so that I am not in so much pain. Can anyone help with this issue?

It's an invalid thought. You're not stupid because you don't understand a puzzle. It's just a puzzle nothing more.

Gonna have to let it go, sweetie....