I'm NC with my dad and horrible sis and haven't had any contact with the youngest bro since my contact with my dad (2.5 years). I also have a nice sis and a nice bro.
I posted a thread last month about my nice sis's DD's first birthday party and whether I should go and how I could make it bearable. I went. My dad ignored my DC (12 & 9) and me. My horrible sis & I ignored each other. I saw my nice bro and my younger bro who was nice to me as though nothing was the matter.
Fast forward to now and I find out that younger bro is having a family meal for a special birthday when nice bro asked if I was going. I replied I wasn't invited. Fair enough. I haven't seen him in 2.5 years other than last month. Nice sis emails me to say she didn't invite me as she thought I wouldn't want to go because my dad and horrible sis will be there and she's sorry that she didn't let me make that decision. This upsets me as I made a massive effort to go to her DD's birthday to be there for DN and to show I have as much right to go to family functions as everyone else.
So I wonder:
A) how come I'm ostracised when the reason I'm NC with my dad and horrible sis is because they are nasty and I'm just standing up against that?
B) why the fuck did I make the effort to go to DN's birthday party after all?
C) how do I stop seeing nice sis and nice bro as fuckers for buying into 'let's leave chicaguapa and DC out of family gatherings'?
D) AIBU to feel really upset and just want to say "fuck off the lot of you" including nice bro and now-not-so-nice sis for C) and just be with my own nice little family and pretend they don't all exist.

Is there a chapter in Toxic Parents about this? Because it's bloody hard when the rest of the family treat you like the perpetrator because you're the only one who can see the truth. 