I think forgiving OM as well as your wife (maybe again) is a great step for you. That has to be incredibly difficult.
My take on forgiveness either learned, experienced, or read is:
I think forgiving him/w does not let them off the responsibility of what they did, you are not condoning their actions, you are not saying they were not wrong.
This is for you. Your anger is not affecting him, its hurting you.
Forgiving him may be a way for you to change the story u have cause as long as u keep the story that he was wrong and shouldn't have done it you are going to feel like he needs to be punished more which is going to rationalize in your mind your anger towards him.
But you are the only one being abused with your anger, it does not get to him.
You are the only one expressing it and receiving it. Its time to stop abusing yourself with that anger, day after day, month after month. The bigger abuse is the abuse we play on ourselves so the one to forgive so we don't abuse ourselves anymore is to forgive ourselves for being angry.
And then we have to accept our own forgiveness.
Be right or be happy, right? As long as we hold the story that we are right, we will feel justified in expressing our abuse and we might be the ones that receive it. And also, if we hold the story we were wrong, we will feel justified in accepting abuse from someone else or ourselves.
In either case holding that story in the frame of right or wrong perpetuates the abuse cause it continues to look for someone to punish.
If we want to get out of this we have to let go of right and wrong and who deserves to be punished or blamed and how much.
The way we do that is forgiveness.
Not easy and not linear, at least in my experience.
