I had an Uncle Bob who I always considered my uncle, long after my mother's sister divorced him. It ticked my mother off that I was somehow disloyal to my aunt, but heck, you get to know these people as part of the family when you're a kid and it is just plain silly to somehow act like they weren't someone you loved all your life. It was fine with Bob, and we used to visit when I was in that area. I think it made his second wife a little uncomfortable, but my cousin (his and my aunt's son) and I were just fine with it.