Just disclosed to my ex

I (26 M) was just diagnosed with HSV 2. After freaking out for a while I decided to reach out to my ex. We broke up 6 months ago. I was clean before her and she swears she was clean before we did anything.

I most likely got it after I we broke up but morally I need to tell her so she would get tested. I am trying to not freak out and she is pissed.

I feel like I just got punched in the stomach and trying to figure out a way to contact my partners since her.