Sorry FIL went over the deep end. Tell me he didn't really break the kid's nose? Just bent it? If he just spat and was gross, especially if he was drinking.... might be forgivable. Do you have a backhouse he could stay in away from the family? If faced with homelessness, do you think he would consent to daily, witnessed medication? A little bit of behavioral counseling might go a long way with him. He parents must have been awful. DO YOU HAVE A LOCK ON YOUR BEDROOM DOOR? Do it
. You know, you could get locks for all bedroom doors while he stays with you. I would make sure they use different keys and that you have a master key for all of them (in your car, of course, where no one could get them). FIL might notice that you put the boy's door back on & even let him lock it, so he would approve of that which is a win-win, at a time when a win-win is needed. And just don't mention the lock on your door, or say if a kid needs one, surely a husband and wife do, too, lol. And let FIL have one, for old times' sake, lol. Everyone needs time out sometimes. The idea could reduce the pressure you feel.
Did you know GD also was arrested in the last few days? It's true. Not as dramatic or violent, though. It was around the time of the new moon, which affects tides. And we are primarily water.
Did the adolescent get his door back on? Better to have a bedroom door that he should develop worse outlets like getting weird in public restrooms or taking all day in the shower, or worse, considering predation. Maybe your husband could get him some girlie magazines, which honestly are usually more wholesome than online stuff. Net Nanny time?
Sounds like a lot of serious stress all at once. Hope you're hanging in there.