A year ago I split from my husband after 22 years of marriage. We have twin DCs aged 10. In 2012 my husband started an emotional affair with an old school friend who he remet on Facebook. She lives abroad and they met up a handful of times (I assume they had sex), mostly it was an emotional rather than a physical affair. They exchanged literally hundreds of emails over many months. I found out after about 6 months and he promised to end it, but 6 months on I realised he was still having this affair. I chucked him out but after a few weeks he came grovelling and I took him back. After that the EA continued on and off for the next 5 years, I kept telling him how distressed I was but he took no notice. Anyway finally last summer I ended it, he was distraught but serves him right. We are now co-parenting reasonably well and are reasonably amicable. I know from my kids that the OW comes to stay every few weeks so clearly they are now in a relationship (they think she's a friend though).
My question is this. My close friends know about the OW but I have never mentioned her to mutual friends. So now I find myself in situations where I'm with a friend of my ex, and I don't even say that there is this OW involved in our split. Something is holding me back from saying anything, maybe need to protect ex or something. But why?
How do I broach the subject of this OW without feeling like I'm muck-spreading? Or should I just distance myself from the friends who also know my ex and just spend time with my friends who I can talk to openly?
Advise please!