On the plus side he is trying to be "Civil" which I think shows there are a thoughts, often conflicting, flying around in his head. But, on occasion, sometimes something passes through the "Civility Filter". That same thing had happened with my wife and I where occasionally something biting or hurtful will slip out after I totally blew up her world view by dropping the T-Bomb. When later we talked and I pointed such things out (best not do such things when emotions are high) she also pointed out, fairly, that sometimes I am also overly sensitive. It took a few months and a lot of often times difficult and emotionally charged talks for things to things between us to mostly go back to where they were.
But, that is because we both put in the hard work needed to keep a relationship going that we both believed in and wanted. Both need to want to make things to work out. Both need to work at it. Both need to Compromise. We, whether you want o believe it or not, are asking our partners to make a ginormous compromise with themselves and with us. Their world view, their hopes, wishes and dreams of a shared future were instantly shattered. Sometimes a balance can be struck. Sometimes not.
BTW - Probably best to make some lame excuse to blow off this family event Saturday and take a long walk among nature to help clear your head and recharge your soul