Should I inform my ex-father in law that his underage daughter is drinking?

[Drew]

If you were a parent of a teenager, wouldn't you hope that there was a responsible adult who cared enough and was bold enough to inform you that your teenage child was drinking and being driven by other drunk teenagers? If you don't want to handle it in the simple "snitch" fashion, then you could get proof, like printing the posts, then confront her yourself and offer her the chance to tell her father herself before you tell him.--"Sally, I'm very concerned about you. I saw some posts on your wall about you drinking and being driven by other drunk kids. As a responsible adult, I feel obliged to inform your father of this behavior. I want to give you a chance to do the responsible thing and tell him yourself, so here's what I'm going to do. In 3 days, I'm going to go to your father and show him the posts about your partying. As someone who cares about you, I can advise you that it will demonstrate a great deal of maturity if you come forward yourself, beforehand." She might resent you for it but you'll have done the right thing.