Hi. Many hugs to you. FB sent me into a depression, too about two weeks ago. It OFTEN makes me feel that my life is not worthwhile because I don't have all the supportive, loving relationships that so many have. It does hurt. I don't blame you one bit.
But try to realize that even those who are posting such things, many of them have problems and, believe it or not, feel lonely. In fact in one article I read, those who post a lot often do it out of a need for attention and guess what? Loneliness! That's right. Not all appears as it seems.
It still bugs me, though. I keep it to keep abreast of events and to participate in the few forums where there is REAL sharing. And there are like a handful I actually like sharing with (although I cannot even say they are real friends).
For me meet up has been much more meaningful and real. That is where you have real face to face time and real conversation and sharing and, the possibility of making real connections. I feel more "alive" on meet up than FB. I feel so many of FB are phony and even though they are your "friend" they never post a "like" or give anything back. That last item really bugs me. I have given attention to many other people's posts but they can't be bothered to give back, even a bit? Just stupid. I actually defriended two people because of it. I couldn't stand it.
Have you tried meet up? That has really enhanced my life.