The only bitter divorces I remember in our family (aside from that aunt) was my own parents. My father was much better about it than Mom, who never spoke to him unless she couldn't avoid it, and around whom you didn't discuss him. I think she put entirely too much energy and anger into it, and it had negative consequences for a lot of people around her. With that awful example in mind, I was very careful during my divorce to not have people pick sides or stop talking to the party to whom they weren't related or weren't friends with first. His brother was a little stand-offish at first, but got over it.
For years, until the neighbor (Bette) relocated to Arizona, we used to go to her house for Thanksgiving. Her daughter and grand kids were living with her for a number of years after their divorce, but the ex and his parents and sisters, if they were in town came over. As did my friend's ex in-laws. When I divorced I asked if we could join them regularly (I used to cook every other year just to keep in practice) so we could be together without having to be just our small group (it was difficult at first). When it comes times for introductions it gets pretty hilarious, describing the relationships and exes through the room. We did a surprise birthday for my ex this year--60--and Bette flew in and many of her kids and their exes (and one fiance--an ex in training?) were all here. A family who we used to see years ago also made the trip, and they're still married after 20 years. The introductions were convoluted and very funny. "We get along better when we're not married to each other," was the way I summed it up after going through the drill.
(The surprise was effective--the kids got him here through a regular routine--our son tagged along for a ride when he picked up our daughter at work and brought her home. He always gets out of his car and walks to the back gate to pet my dogs before he leaves. This time there were 17 people standing in the shade on the patio waiting to greet him. It was priceless!)