How to get over HER after cheating?

My boyfriend and I had been together for ten years, three children together, when I found out he was cheating with a married woman with two children on her own. She knew about us. I saw it in their messages. Now we separated and I'm over him. I don't miss him or anything like that. I'm sad for our children, but that's it.

But she has a common name, think like Jessica, and everytime her name comes up I hurt. I get upset and it affects my day to day life. It's to the point that if I'm going to buy a shirt and the shirt is called Jessica I won't buy it because of the name. I know it's ridiculous, but I dont know how to stop being upset with her. We separated about three months ago.