If I were in that position, I'd be quickly firing off an e-mail to Dad with a subject line that said HEY DAD DELETE THAT MESSAGE WITH SUBJECT LINE ___!! Then explain in the body that it was meant for OH (BTW, I'm not familiar with that abbreviation; is it Old Husband? Only Husband?) and you sent it to him by mistake. If he's a big boy, he'll do as you say. Dads do *not* want to read about their daughters' scrabble games! (If you're worried he'll read it out of nosiness, then just tell him it has to do with work stuff or weekend plans or something else he'd have no interest in.)
Anyone else hearing Officer Barbrady from "South Park"? "OK, people, move along! Nothing to see here!"