Lots of advice on here to take steps, such as hiring a lawyer, seeking various interdicts and making police reports, which potentially escalates this very significantly - not only in seriousness, but also in terms of the emotional and financial toll on the OP.

That may be the right course of action for OP, but there's a good chance a better course of action would be to move on. People do get allocated to rooms which are already occupied - it shouldn't happen, it's not common, but it is a frequent enough occurrence to be oft-reported. The chances of the person who happened to have been allocated the room also being one of the very small percentage of people who are bad actors inclined to take advantage of such a situation are minimal. Sure, his reaction didn't sound like what I think my reaction would have been, but in such a situation both parties are likely shocked and a) might not act perfectly, and b) might not interpret the other's actions perfectly.

While it is too easy to say that the best time to sort this out would have been there and then, rather than going out until 0300, it is also true. I'm not sure what more, realistically, can be achieved now other than prolonging the stress and running up a legal bill.