Back story .... DH has been in DS life since he was 4 and moved in with us when DS was 6. DH and I then had 2 DC relatively close together. DSs DF has been very present throughout his life (although very much a Disney dad with very lazy parenting ideas) and they have a good (albeit more like mates) relationship.
DH and my ex could NOT be more different. DH can be strict and authoritative and this was always difficult for DS, especially after spending time with his DF. DSs teenage years were typical (IMO) messy room, answering back etc. DH found this hard as did I, but my motto was 'pick your battles'.
Fast forward to last Nov (2nd lockdown). DS is now 17 and working full time. Not sure if the trigger, but he basically lost his shit, punched his TV and was in tears. Obviously I followed him to his room to see what the hell was going on, but he was too angry to talk. DH came up and DS screamed in his face 'this is all your fault'. I told DH to leave the room immediately and sat with DS till he calmed down. When he did he told me that he couldn't live her anymore, that he hates my DH and he had been wanting to say this for a long time but didn't want to upset me. He asked if I could phone my DPs (who he has a very good relationship with) and ask them if he could stay there for a bit, they agreed and said let him stay for a week then we'll talk about it. So off DS went. I was obviously distraught that evening and couldn't speak to DH about it. Unfortunately the following week, I caught Covid and was reasonably poorly with it. So the week at my DPs turned into 3.
When I could leave the house following Covid, I went to see DS and mentioned about coming back home and that things would change at home (I had talked at length with DH about the situation in this time) But my DS said he wasn't coming back.
It's now been a year. DS still at DPs house (thank fuck they are wonderful ) . I see him at every opportunity I have along with my DC and our relationship has never been better. Although I realise this is because I'm not having to pester him round the house etc. In this last year, DS has not stepped foot back in his home. Unfortunately DH works from home, I think he would have come around if this wasn't the case.
I'm completely worried about Xmas day plans. We always go to my DPs in the day ( we did last year, and DS just blanked DH and they both just bit their lips, not a great atmosphere but it was nice for the other DC ) Recently it was my DFs birthday, we all went around for a couple of hours, DS did not come out of his room due to DH being there and it was all quite upsetting for me that he choose not to (although I understand that he would have felt uncomfortable) I just don't think he would come out of his room on Xmas Day if we went around. I desperately want all my DC to be together on Xmas day but I don't see it happening. DH is of the option that DS is an adult and just needs to be grown up about it.