I'll start by giving you the background details.
I have 2 sons, the oldest is 26 and the youngest 24.
My oldest son has been in a long distance relationship with a woman from Norway for the past 3 years and will be moving there to live with her at the end of the month. He has aspergers and has been adamant his entire life that he doesn't want children, he had the snip 5 years ago (which he proudly told me about). His partner also feels the same way (and is also 8 years older than him so time would be ticking for her if she did want children) that's how they connected when they met online. I am sad about this but I have to accept it because I love my son. My other son and his partner have my 4 year old grandson who has severe autism and is nonverbal. I invited both of my sons and their partners over for dinner just to spend some time with them before my oldest moves abroad, his partner is also visiting and joined us. A few hours go by and we're just having a nice chat when my grandson starts having a meltdown and screaming. My oldest turned to his partner and loudly said "I'm so glad we'll never have to deal with this shit" and his partner laughed and said "I'd probably shoot myself if I had to deal with that" and they both thought that was hilarious. My other son heard that and stormed off in tears. My oldest son and his partner left shortly after and I've spent the past hour consoling my son with his partner. They really struggle with my grandson and his needs and that comment tipped my son over the edge. I'm disappointed in my other son and his partner but I don't want to sour our relationship just before he moves away. I don't know what to do.