Hmmm...I'm not buying the innocent, playful little brother routine tbh. he sounds like a wind up merchant.
OP - did your dc see all this going on? What a nightmare!
I sympathise with you greatly - in your shoes I'd be sickened and disgusted with my dh.
To be honest with you, I'd probably never invite someone my dh didn't like, to stay for 10 days...and I'd be pissed off if he did it to me....but then, I'd never invite anyone to stay for 10 days, beloved or not. 3 days is the maximum I can bear of any guest.
I think this is a case of build up and temper lost. I reckon your dh dislikes your brother...I think your brother knows it, and relishes winding him up as only a 19 yr old lad can, and I think your dh has made a complete and utter arse of himself over it. Oh fucking dear.
I don't think the police are required - I agree with worra on that score. They scant be interested in this carry on.
I think your dh is going to be feeling pretty fucking horrible and stupid right now, because what he did was horrible and stupid. I am not surprised you are re-evaluating your marriage right now. Are you happy with him generally?
I think your brother might think twice about taking the piss out of his sister's husband again too.
On the whole I think this will blow over, but leave a very sour taste in everyone's mouth.
You might want to think about your dh's temper. That's pretty dreadful.