I can only offer you the advice I have been given on another forum, that one dealing with being Children of Hoarders.
In dysfunctional families it is common for one person to be, as you said, the scapegoat. This can permit the other members to shove their misery off onto you, and thus avoid the discomfort/anxiety they would feel if they looked hard at themselves.
Communication with people like that is never pleasant, and it rarely improves, because they rarely change. As the posters above have noted, setting your boundaries is vital. They are all you have to protect yourself.
I have been told over and over on this other forum to embrace the Black Hat. Since they will label you the villain no matter what you actually do or say, claim the title, wear it with pride, twirl your moustaches, tie people to railroad tracks. You know the truth of who you are, those non-dysfunctional people who love you know the truth about you. Sadly, your biological family, unless they seriously work on themselves, never will. You can break your heart and lose your mind beating against the wall of their mental issues.
I feel for you, and wish you the very best.