I know it's hard but it beats giving your son's eyes another reason to bulge out tonight. It also beats giving the the OK (other kid - the 19 yo one) any satisfaction. It also beats a backslide from hell and though I know it would feel good just to blow for a few short minutes the aftermath ain't worth it.
Take the high road. It'll be over soon.

Then you can think about whether or not you're going to let him come back into your house and eat your food again while disrespecting you like that right in front of your son...