This is the effed up mentality in my family and beyond.
My father was chronically unfaithful, both with my mother and with his last wife, the one that became his widow. His reasoning was that he saw my grandfather doing the same - the big problem is that my grandfather remained widowed early on and never remarried, so of course he was free to do as he pleased.
My mother and my father's widow completely agree on the fact that men are predisposed to cheat and always cheat when given the opportunity, and if they don't it's because they can't and are unappealing to women. This topic came up during our aperitif, and I did get a bit upset because I never cheated on my wife, and neither I am unappealing to women - I just have the morals to not cheat. They said I was a liar and I haven't cheated on, but surely will in some ten or twenty years.
They laughed at me, my wife trying to keep me calm and saying they just acted like that because they drank and leave them to be the gossipy hens that they are. The part that irked me the most was my mother who kept saying "Enough or he'll start crying" and then again just laughs about how I should have become a priest and so on.
I didn't even get angry with her or raise my voice, I just packed up my car and drove off to my grandfather's house.
I didn't take her calls, just wrote her were I was going (literally ten minutes away), she just replied "I messed up, didn't I".