Drive over to the guy's house the day they get back from vacation. Lure him outside and crack him over the knees with a bat. Proceed to curb stomp his face.
As he's lying lying there in a pool of blood, teeth fragments scattered about, explain to his wife who is now crying hysterically ("what have you done!") that she's nasty, a lousy wife, and a horrible mother.
Then turn you attention to little Johnnie and little Suzie, standing in the doorway, overcome with terror. Crouch down and with a little smile, patiently explain that their daddy is a home wrecker, how he no longer loves mommy or them, and to understand that there's a good chance they're both adopted. Grab little Suzie's juice box, slup it down, toss it aside, and make your way to the car.
A couple donuts on the front lawn, a crushed mailbox and flower bed later, you're work here is now finished. Drive off into the sunset with middle finger firmly extended out the window.
I know, I know, totally inappropriate. But a scorned husband can still dream, right?
Besides, I got anger issues. This is just how my brain works in the heat of the moment.
You forgot the oodles of money you will now shell out to him after he sues you and you're in prison for assault with a deadly weapon.