It's Facebook. OF COURSE it's like this.
Look, part of the whole freaking point of social media... even if a lot of people wont admit it... is to get on there, find something/someone you can look down on, and then shout about it so that you can feel superior to whatever/whoever it is you're shouting at. More specifically, to feel superior IN FRONT OF OTHERS, so that they too will think you are superior (insert facepalm here). And so, that's exactly what a lot of people do, and the true reason why many use it. As such, Facebook is *extremely* toxic. That sort of behavior pervades pretty much the whole thing, because it IS the whole thing. A place to show off, put others down, or both at once.
So no, it's not fair that happened to you... but it is NOT unexpected. Instead, it's freaking Facebook: that's what happens on there all the bloody time.
While it may not have been fair... it may have been a stroke of good luck. Now you can go find a non-Facebook group or site that doesnt blow goat chunks. I have no idea what that even means, I keep saying it whenever I find something worthy of it, and Facebook groups fit the bill.
Best advice: Dump Facebook. And any other form of social media. It's toxic, and it sure as heck aint doing you any good. And before you say "but I gotta keep in touch with so-and-so", let me present to you this revolutionary idea: phones are a thing you can use. It turns out phones can do things that arent just Facebook... who knew? Keep in touch with people through actual phone calls, or normal, direct text messages.