This is a bit fraught so will try to explain.
SIL and exBIL broke up almost 2 years ago. It was a difficult relationship and he was emotionally abusive, controlling etc. She was very reactive too so all round bad. She earned all the money with one of their ongoing issues being he worked minimum hours for minimum wage while also NOT doing childcare, home stuff etc. The relationship end wad therefore even worse and his behaviour has been pretty appalling to her as well as to the rest of us - he blames us and has form for sending long rants aggressive messages, being rude in person etc.
They continued to live together for a while so we all had Christmas together at their house 2 years ago. Last year we had Christmas at our house and we were asked to include him for the sake of their dc. He still regularly is there for SIL led family activities including of course things like their dc's birthday.
But I hate him. I hate how he treated and treats SIL. I hate the way he has treated me and dh. I hate the fact that his attendance drags everything down as he walks around with a long face, doesn't make any effort, and largely ignores his own dc. Made worse as they need constant supervision which he refuses to give. Him and SIL inevitably also get into arguments as a result of his uselessness.
So don't want to see him this Christmas. My view is that it's supposed to be a out spending time with people you love. But dh, understandably, feels conflicted as he doesn't want to upset sil and their dc. We did talk about going away for Christmas to.avoid the issue but cash and other logistics mean we can't.
It's causing tension. I honestly have no idea what to do.