I can relate to this, it's a bit too personal but trust me, you're not the only one, and i'm very sorry this happened to all of you. you were lucky to have known some honest friends. (though, me story is quite silly, but i'm not going to reveal any names.)
I have bad taste in men. apparently always have until now. I did date someone, i won't say who, but we had been roleplaying for quite awhile. They were happy with it until a few months in, when they vanished. I waited for a few months, they finally got online once and when I said hello, they explained it was not them, but their sibling, and that they were also ill.
three months later that person came back and explained that they had died, and I was quite shaken over this. Naturally, I never heard from them again.
But this is when it gets funny.
I saw them a year later with the same friends as before, same person.
Needless to say, it was irritating, and my friend (whom we all know as 'Claire Redfield') was with me for most of the time i was with the individual. Yes, she trolled them. and yes, they deserved it. because I learned from their close friend it was all a lie.
You people were lucky to have honest friends, I think iw as getting karma'd for something, i don't know what. but that was a few years ago and, trust me, i'm over it. (though i wish i still had those logfiles, Claire sure was funny.)
but, again, i am sorry this happened, you were lucky to have good, honest people there. really. it seems they're hard to come by in real life. but that's why we have the internet, it makes finding them easier. I've had two other relationships that ended in lies like this, my expectations of humanity are not very high.
But the fact that someone was honest and nice to you, and was a good friend to you, is always great. I'm terribly sorry for your losses.