My oldest turned 12 yesterday and he chose to invite 5 friends to go paint balling with him this Saturday. He invited a kid that I don't know well, but had taken him to an event so he was kind reciprocating. For the past 2 weeks the Dad has been coming up to me at pick-up and questioning/border line harassing me on why I would let my son choose to go paint balling. I finally told him if he didn't think it was appropriate then he could decline. Well the kid came up to me the next day and told me he's going and he and his Dad came up with a plan to "show C what it really feels like to get shot" and "that's what he deserves for choosing paint ball". I talked to my son and he said that he told him that he was going to corner him and unload his gun (250 paintballs) at close range. I told the Dad the next day that I didn't find his son's comments appropriate and maybe he should just stay home.
So he's been harassing him at school and today the Dad got mad/confrontational with me about it and I stuck to my guns and said yes, I told him he couldn't come, I don't need a fight at his party.

Sorry that was pretty long. Did I handle it ok? I'm feeling guilty because I see these people everyday. Would you have handled it differently?