I want to sleep with you. I don't mean have sex. I mean sleep. Under my blankets. In my bed. With the window cracked, so it's chilly and we have to cuddle closer. No talking, just sleepy, blissfully happy, silence.
You are not the exception to the rule. You will not cure them of cheating, because you're an awesome person. A cheater will always be a cheater. Especially, when they are cheating long into adult years.