Where is this coming from

I've been stuck in sadness for 2 days. A hint of anger pops out every once and a while but mostly just sad. What the heck is wrong with me?I feel like I did when this started. He is in my head like crazy and I want him out.
Yesterday someone that I know mentioned his name, I stopped them and said I don't want to know. They said oh no, you will laugh and told me that my exN had requested a girl that I know but he does not know on Linkedin. There is no business purpose for them to connect, it is simply because she is cute. He also knows that I had a falling out with this girl several years ago. I didn't want to know any of it. I was already really down yesterday. Now this just has me spinning.
I think the hardest part for me to get over is the fact that I did nothing wrong to this man. He tried projecting things on me but honestly I did nothing wrong. I was a great wife and great step Mom. Now he is online looking for new or additional supply and he picks someone that he knows has a hurtful history with me. I've been hurt enough, why keep going?