Confusing story so if you can get through it, well done :)
My uncle (let's call him uncle A), left my aunt of thirty years for another woman about 18 months ago. He was seeing her in secret for ages but everyone knew (including my aunt) yet he kept denying it. He left her and their two children (teenage and young adult) and moved into a flat in the same town. He still goes round to the family house to see his children sometimes but it's always frosty.
His new woman, who is also married with young adult children, moved into a flat near to him and that was that.
For Christmas he started getting upset that my aunt and his children were going away to see her sister and that he would be left 'alone' on Christmas day, as his girlfriend was going to spend it with her husband and son.
The uncle is my blood uncle but I'm very close to my aunt. İ used to be close to my uncle but since he started his new life he stopped making any effort with any of us.
Anyway, for Christmas my other uncle (his brother) invited me and my DD over for Christmas dinner along with my dad. İ said shall we invite uncle A, because he's going to be on his own? After Uncle A was invited he then suggested that we all go and spend Christmas in my aunt's house instead (which he refers to as The Big House) as it would be bigger and nicer. Me and my other uncle said to one another that we wouldn't want to go to my aunt's house for Christmas as it would be weird using her house for Christmas without her there and she definitely wouldn't like it, so we said no. İ also said that I could just imagine uncle A's new woman coming round for a drink.
Fast forward and my aunt was telling me about my uncle giving her abuse again for not staying around for Christmas and I warned her about his idea for her house. She was furious and then told me later he had poo-poo'd the idea of spending Christmas with his brothers and İ. Anyway, in the end İ decided to stay home with a friend as I'd just moved house and didn't want to travel, but told my dad and uncle they were welcome to come to mine with uncle A, but they all did their own thing.
Spoke to my uncle today about meeting up and he said he got a text from uncle A this morning saying he'd had a great Christmas and he had spent it with his girlfriend at 'The Big House', basically he had Christmas with his new woman, who was an affair partner to begin with, at my aunt's house behind her back.
Now my other uncle is saying he wishes he didn't know about it as he feels like a horrible secret keeper. İ said İ was going to tell my aunt, because it's out of order, but he said please don't, as it will cause a big row and he will be seen as a secret keeper for not telling her. He said he only told me because İ had predicted it happening and he couldn't believe İ was right! He's now stuck between betraying the trust of his brother, or betraying the trust his sister in law who he has known most of his life. İf i keep it secret, İ'm betraying her trust, but if İ tell her, I'm betraying the trust of my other uncle who was told the secret. I'm not bothered about betraying the trust of Uncle A, as he's basically written me off for making effort with me these days.
What would you do if you were me?