Oh man, that's a huge money. Sorry for your loss.

I've never heard of oxapay nor can find much trace so it's safe to assume they don't have any reputation to lose. They probably will just move to another domain after some time, unfortunately. But it's good you're posting in communities so some others may be warned.

You can check if perps moved your BTC to a centralized exchange but pretty low odds of making a difference as they might have withdrawn the money already and/or getting authorities to cooperate 1 on 1 with exchanges ain't easy as well.