I'm going to tell my friend's wife that dude is spending like 8 hours a day playing hentai games on steam
That is a lot of time. Do you think she doesn't already know?
She was too dumb to find out about it.
I don't think that's particularly fair of you.  It's not really your business what your friend decides to do in their spare time.  Let him be himself!
NO, MY FRIEND IS A DUMB IDIOT AND HE IS PATHETIC. HE IS JUST WATCHING PORN ALL DAY.
That is between your friend and his wife. You need to let him live his life.