I am somewhat stunned by people on this thread reprimanding you for terribly bad manners when you asked the host if it was ok to start.
If I have cooked and there is a bit of a delay getting to the table I make a point to actually tell people to start as I don’t want all my efforts to go cold and be ruined. I want people to enjoy it.
My children have been taught to wait but do ask and I always say yes go ahead.
This man asked permission and received it. Even if this did offend someone else they clearly didn’t have the emotional maturity to tactfully deal with the situation with good manners themselves and perhaps gently mention that on this occasion could you just hold on whilst we say Grace.
Incredibly rude and disrespectful to belittle your elder at the table plus the carer of your child and a guest for that matter.
I am unsure why the host herself did not step in and defend / calm the situation as they gave permission.
I can fully understand why your feelings are hurt as it’s humiliating to be treated like that.
Even worse to then be sent a rude text in reply. The son appears to be a nasty piece that of work.
I would be worried to about how that behaviour reflects on your grandchild.
That all said, I don’t think it’s fair you tell your wife what to do. It’s up to her to decide how to respond - whether that’s siding with you or not. It’s not right either to try and control how she continues the relationship with them.
The issue is between yourself and this man. However if I was your wife I’d personally have got up and left the table and gone home with the grandson the moment my husband was berated. I would not have tolerated abuse like that towards my husband there and then.
Im sorry this has happened to you, I would leave it for now. This other man has just shown himself for what he is. Don’t fall into the gutter with him and don’t let it cause an argument with your wife. Just tell her how you feel about it and that you are finding it difficult to have a relationship with him at present given his awful behaviour.
Leave it at for now. Be the bigger person.