A Facebook surprise

I think maybe I don't understand Facebook. Today I got a notification of a message from someone on 'Messenger.' I don't use Messenger. To be honest, FB is complicated enough for me without adding  Messenger. But this message could have been important or from some one I knew so I thought I'd check it. 

I clicked on Messenger (top left hand side of my page). The message I was trying to check out wasn't there but, as I scrolled down, I found dozens of messages from way back in 2015 and 2016 from total strangers and all of them insulting. All referred to my appearance or my age or my political views and a few pretty menacing messages warned me that I'd better give up posting on FB - or at least stop posting this kind of 'stuff.' All of them were anonymous: 'from a Facebook member,' nothing more. 

So here's what I have to ask: I can't remember what I posted that could have provoked this rage - and it is pretty rabid - but can I do anything about it? I don't mind the usual back and fro of FB discussion, but this is different: there's an air of menace here. It seems to have to do with my nationality, my sex and my politics, and although I'm happy to admit I'm in favour of independence, nowhere have I ever stated I am SNP. 

Is this how things are these days? People can be anonymous on FB so they can send offensive messages to total strangers and there will be no come-back?

What bothers me is that in among all this shite from trolls were two messages from people I really wanted to get in touch with, because really we need to keep human discourse going.