I (36)f was in a serious relationship with (54)m when I discovered he’d been having a multiple years long affair with a married woman. As a result of his infidelity, our relationship ended. About a month after we broke up, I ran into his daughter in law in a public play place. We were the only two adults with our kids and when she started small talk with me, I disclosed that I knew her via her father in law and that I was his ex girlfriend. She excitedly introduced herself and we exchanged a few pleasantries. She then asked me if we were still dating and my response was “No, he cheated on me.” Her response was “I’m so sorry. He’s made a lot of mistakes in his life.” I told her I still thought he was a good man and that I missed him and hoped him well. I gave no other details whatsoever and we chit chatted a bit longer and parted ways. My ex thinks that AITAH for disclosing that he cheated and I think it’s very fair and valid to tell the truth and that I’m NTA in this situation. AITAH??