What should I do?

So me and my now ex were dating for 3 years, during this time I never had sex with her as i’ve been sensitive and never felt comfortable, yes it’s my fault for not fixing this problem for 3 years, she did mention it here and there but never took action i’ll take accountability however we did everything else under the sun.

The problem I have is that as soon as we broke up she got straight into another relationship with a guy that she had emotionally cheated on me during the relationship i now know for sure. I told my ex before we broke up that I want our relationship to be kept private and not tell anyone about our sex life etc and personal issues i have and she agreed to never say anything.

Now i’ve heard from someone that her new guy, has spread the information to people and has gotten back to me and around to my whole friend group now about how my dick wasn’t working and how we never had sex. Hearing this felt like a stab i feel so humiliated and so angry, I feel like i need to say something to her in person as i bump into her at the gym and say what has spread and how i want our relationship to be kept protected, i don’t know what the right cause of action is as i also don’t want any more information to be spread.

I feel like it wasn’t her intention for the information to be spread she probably told him to never tell anyone but obviously that’s never the case.

We ended on good terms everything was civil and understanding, she even wished me a happy birthday a month later it’s not like she thinks i hate her she doesn’t know the information i have found out and she would be shocked if i knew.

And how should i respond to my friends as I don’t want anyone to know that true i’ve mentioned to them that his lying and spreading rumours, but at the same time why would he lie about that. It’s like it’s obvious it would have came from my ex but do I say my ex is being toxic and insecure or something idk how I should also respond to people who would bring it up to me.