The first thought that comes to your mind is hatred when someone you love has cheated on you.
You want to get back at him / her and hit where it hurts.

After sometime you start remembering the small good things favoured on you by the same someone.
You still want to teach him / her a lesson. Maybe a showdown to confront, to humiliate.
The further you think, you remember a few more small good things favoured on you through that same someone.
You still want to talk and give a piece of your mind and clear it.
The further you think, you have forgiven and forgotten the whole episode and moved ahead in life.
Forgive, if you can survive, in spite of the cheating.
But not at the cost of someone or something who you are responsible for.

Anger is self destructive...

self defeating

Anger depresses...