a dear john

A woman found out that her husband was cheating on her while stationed in Saudi a few months ago. So she sends him this care package. He is excited to get a package from his wife back home. He finds that it contains a batch of home made cookies and a VHS tape of his favourite TV shows.
He invites a couple of his buddies over and they're all sitting around having a great time eating the cookies and watching some episodes of South Park.
Right in the middle of one episode the tape cuts to a home video of his wife on her knees sucking his best friend's private. After a few seconds, he does his business in her mouth and she turns and spits the load right into the mixing bowl of cookie dough.
She then looks at the camera and says, "By the way, I want a divorce."
Now that's a Dear John letter