@Findingmrright,
You'll have to talk to him directly about his behavior.
"Jeff (or whatever his name is), how do you think the visit went?"
Listen to what he says. If he somehow thinks everything was wonderful, then he's going to have to be schooled that it wasn't.
"You didn't make a good first impression."
If he asks why, tell him. "You were rude to my Aunt Mary. You tried to monopolize my time. You argued with my father at dinner. You didn't offer to help with the dishes." Whatever the issues are, he's got to know.
And then you can approach your decision from a better position.
Maybe you
should leave him. Someone who doesn't make an effort when meeting the family for the first time may not be taking your relationship seriously.
Or, maybe your family is overreacting.
Only you can really answer that. But in the meantime, if he doesn't know what the problem is/was, or he plays dumb, tell him.