OK, so how are you going to ACT on the confronting?
A letter? In person?
I recommend one of these two- phone conversations are nasty! If in person totally freaks you out, start with the letter. If they call you after, and it starts to go south, you need to set a date to discuss things in person. People need time to react, and my predication is that it probably won't be pretty. Be prepared for that, and hopefully it will go better than you think.
God bless Marc for being supportive and not shooting back! That takes a strong man... he's a keeper!
Good luck.