I'm so sorry this happened to you.
Block him from all forms of social media. Why? It's not to be vindictive and do a kind of tit-for-tat response. Rather, it's because you're looking at pictures of him with his new girlfriend and it's bringing you down. So keep your nose out of that and you'll at least feel better in that respect.
As for the remainder, are you able to afford to stay where you are? Can you make friends at work? Can you find another job if you're still working with him? Can you return to your own country and get settled there?
You don't have to specifically answer me at all on this thread, but those are questions you should be asking yourself. You might find you need a roommate, for starters. Or maybe you can call your folks and go there and just quit your job. Or maybe you can find another job and make some friends - who won't remind you of how big a jerk he turned out to be.
You're gonna be okay.