Your capacity for emotional restraint is important for your children’s long term well-being.
Late FIL fought in WWII on the Italian side. I grew up in Britain as the child of two parents born close to the end of the war. As you can immagine there were so very many conflicts between his world view and mine.
He was a good father and grandfather. As imperfect as any other human. But he had his own personal mix of good qualities. I cannot pretend that had I been born in his time & place my world view would somehow be exactly the one I have now because “I’m a better person”. Had he been born in another time and place I doubt his outlook and beliefs would have remain as they were.
These are your children’s grandparents, your spouse’s parents. If you allow your emotions to be a mountain of conflict, or tense atmosphere in their family life you are choosing to sacrifice family harmony for your own emotional sake.
If you instead reduce it to molehill size, accept that sometimes gritting your teeth and refusing to react is the best foot forward, you can allow the family harmony dial to turn up again.
You can’t help how you feel. But you can help what you do. Part of the doing is working on getting feelings into proportion. Easy to say, hard to do. But with practice (this will probably include mucho one step forwards, two steps back from time to time) it get easier.
It is for your own personal benefit too. Life is harder when any minute an unknown fact about another person can ruin your headspace. That’s like living in an emotional minefield, never knowing if you can trust the seemingly relaxed and calm landscape to turn on you suddenly.