I know I was apologizing, and I'll bet she was, but neither one of us could hear the other!
This is why it is good that some time has passed. If things are done in the heat of the moment or out of desperation then nothing will be heard. But, time has passed, you have cooled down, he has cooled down and you could really put some thought into this.
Mine was actually an email. It wasn't too terribly long, probably would have been about a page and a half if printed. You need to be very careful of what you say though. Take some time and put some thought into it. I think it is good to let him know that you don't blame him for everything that is wrong.