The Best Thing That Ever Happened To Whom?

Whenever I lose someone i take it hard, my parents, my boyfriend, my best friend etc i torture myself for years about where i went wrong because I thought that they were the best thing that ever happened to me but you know what? Where my ex and ex best friends are concerned Fuck that! Fuck them! Maybe I'm the best thing that happened to them? Maybe it wasn't me that fucked it up?
I'm fiercely loyal, honest, caring, giving, fun and I'd do anything for the people I love. If someone turns their backs on me especially when i need them most (like for instance being put into a psych ward after my mum died) then it becomes indellibly inscribed on my soul that I deserved it, I must've done something wrong, it confirms my deeply held belief I'm not good enough, I didn't deserve THEM. They didn't deserve me dragging them down.
Here's the thing though, i know its tough having a friend or living with someone who has depression, anxiety, self-harm issues. I live it every single day. When I'm low I retreat so I don't drag people down. I suffer in silence. I keep the worst from them because as is always proved to me, they don't actually want to know about it because they don't understand it. They scold me for not asking for help or for not asking to meet but then they don't ask me out anywhere! It's a two-way street or at least it's meant to be.
I do sometimes put on a happy face when i really don't want to if it's a special occasion like a wedding or birthday or something. I must be good at it because they always say I'm on top form even though inside I feel like I'm dying but on the outside I'm the class clown and I'm treated as such.
I'm tired of it. So tired of it. I can't tell the difference between true friendship and pretend anymore with some of them.
Who's loss is it? Who's fault is it?
Why was I ever fucking born? Why the fuck should anyone care?????