FIL and I seem to be two people who simply don't get on - but I'm not sure how to deal with it for the next decades. DP and I have been together for 20 years, married for 10 and one DC (8). As I don't have any family anymore, there is only one set of grandparents who are visited regularly, especially on Christmas. And since they live abroad, it's usually a week or so.
I get on very well with MIL and FIL adores DC and DP - but is very indifferent towards me. There is no hostility - he simply ignores me by simply not engaging with me and being very monosyllabic otherwise unless I disagree with him (e.g. about treatment of DC) when he snaps and disappears.
We are quite different: he has his own business, works alone and probably hasn't been challenged (in conversation) by anyone for the last couple of decades - he always got his way and never had to consider others. While I'm reasonably successful (traditional people would usually have high regard for my profession - although I disagree), I have severe mental health problems with anxiety, depression and in particular a very low self-esteem. There is a long history to this, I have treatment and FIL is aware - he was told by DP - but nothing changes.
When trying to be more rational about it, it looks very much like the problems many wives have with their MIL (believing DC could have done better and resenting new partner) - just a male version with less talking and more sulking.
Unfortunately, the problem with mental health is that it doesn't really listen to rational reasoning. I want my DC to have grandparents and don't want to deprive DP of her family - so I agreed to visit at least on Christmas. But it is likely to be difficult: any suggestions or recommendations on how to deal with it?