Wow, that's a tough one especially since they go to your church. Definitely sleep on it. I don't know if saying anything to them or emailing them will even to any good as it sounds like they knew exactly what their kids were doing and saw nothing wrong with it
. I understand the need to say something to them but I can't help but wonder if it wouldn't be better to just let it be and if the opportunity for them to invite themselves over comes up again you could say "no" and tell them exactly why. Now if the kids were being sneaky and the parents didn't have a clue as to what they were doing it would be different. These people are a prime example of why there are so many bratty kids out there. The parents have no respect so why should the kids! It's pretty sad. I'm really sorry you had to deal with all of that