I know what it must feel like, at least in some parts. I had someone in FF14 in my old FC that I truly saw as a friend and trusted her. Yet after years I was put aside for a another person and it really hurt but at that moment I decided that game is never worth such pain so I went away from the FC, created one with only a real life friend that I could trust and since then it got better. Now I only feel pity for that person.

At the same time I had another person that was nice on the outside but turned out to be a really horrible person. I was not the only one. that that person hurt with their behavior and it seems that they are FC jumping, maybe to get a kick out of that? Either way I sometimes get the feeling that those players are never truly punished, while others are banned for the smallest things.

The best you could do is trying to forget them and start to be a bit more slower with ingame friendships because if you do not know them in real life you will never truly know who they are. Also if you feel like this is too emotional for you try to get away from it a bit. I first thought that it would be the best to try to save the "friendship" but over the time I realized how it was influencing my real life too so I decided that it was enough, and this was the best decision I could do.

Friendship is never all about sunshine and rainbows but a true friend will never behave like that so you should not call them friends anymore. And if you see that you cant overcome it, dont be ashamed to call for help in real life.