Dear {Husband},
I just want to start by saying that I am so sorry that I {behavior}. It was absolutely unacceptable, and I didn't mean to do it at all. I was angry because of {behavior}, but that was no reason to act the way I did.
I really believe that if you can find it in your heart to forgive me, we can work through this. I understand that right now, you're too angry to talk to me, but when I think of all the happy times we've had together it makes me so sad to think of us fighting over this.
Remember when we {happy memory}? Or when we {happy memory}? Even though we're having trouble right now, I know we're strong enough to get through this together.
I love you more than anyone else in this world, and I just want to find a way to make this right with you. I'm so sorry, and I'm looking forward to working this out with you.
With love,
{Sender}