First off, no matter what, a drop off that is that abrupt does mean another guy. That is on her because she can't be honest about it.
Second off, not getting real closure sucks, but unfortunately sometimes it goes down like that. If she won't let you have that closure, it means she is doing something wrong and she knows it, if nothing else, let that be your balm. If she does come running back, you can get your closure then.
Third off, the hardest thing about ending a relationship that your family endorsed is telling them, but the best thing is to do it and get it over with because otherwise they are going to push you with not only the uncomfortable 'what went wrong' and 'what did you do' when they finally do find out, but they will then follow up with, 'what, you don't think we are important enough to tell when something like this happens'. The former is bad, but you can deflect that, the latter is worse because they will be right.
I am not going to bombard you with things like 'plenty of fish in the sea' and 'things will get better' They don't help and you will figure the truth of those platitudes on your own with time. Instead I will say, enjoy your single time and save up that money for the next girlfriend cause it will all be gone as soon as you get your next one
