Think its wrong that I'm going to tell my boyfriends parents he used an egg donor?
Why would you tell his parents something that is so private to him?
He acted like his kid has the same genes as me so I'm going to inform his parents.
I'm sure this is hard for you, but you shouldn't reveal his private information to his parents. Try talking to him instead and let him know how you feel.
He cheated on me and I'm going to get payback.
You two need to work out your issues but you should do it in private. Things like this should be between the two of you and not his parents or anyone else.