Background me and ex have known each other 8 years but live in different countries so have gone have very long periods of time not speaking and it’s very on and off relationship wise.
We then reconnected properly and he wanted us to get married and then backed out and obviously that ended things and he moved on very quickly.
Fast forward one year, they are no longer together and we are talking again. Yesterday we were FaceTiming and he mentioned his ex’s daughter and how talented she was as an artist, literally speaking for a good 10 minutes about her and I was just 
I genuinely have nothing against his ex or her daughter. It’s just that they aren’t anyone to me and they are people I have never and will never meet so aibu to have stopped him and told him that I really don’t care? And that it’s actually a weird subject to discuss?