The story: Trigger warning

Alright, so I tried to abbreviate when I came here, and I understand I didn't give a clear picture. If anybody has the time to read this and give advice I extend my gratitude in advance! It's gonna be a sit down read.
So, my family is small and has 3 branches: My mother's side, being my mom, step father, and grandma, and a few grandfathers I didn't really know. They are noted for being very loving, although my grandmother take this to unhealthy, manipulative levels. My mother is very loving, but my step father's problems come first. My father's side being my dad, grandfather, uncle, aunt, and various relations, they are cold, distant, work oriented, and will actually forget my sister and I exist except at the holidays which are mandatory participation. My sister. She con'ed her GFs way into living off of us. I want to be super clear, I don't care if this was a GF or a BF, that's not the issue. They used false pretenses to live off the family into their 30s, not bothering to get jobs. I believe my sister is sociopathic....she doesn't care what she has to say, as long as she gets what she wants. She has switched sides in the family feud as many times as it takes it keep getting money from someone.
The feud: It started with my grandmother. After my parents divorced, she moved in. My sister and I were small and it was that or lose the house. My grandmother loves everyone in her own way, which means, you do what she wants. If you try to defy her it's everything from losing her love, to her taking her money and leaving, to her threatening suicide (and spending the money first). You can defy her simply by doing anything she doesn't approve of. This was my childhood. I remember her scream crying at us about how awful we were for not putting laundry away correctly.
Some years later, I'd been moved out for some time. My mom, grandmother, sister and GF continued to live together. At some point an argument happened. My mother realized she didn't have to take my grandmother's domineering anymore and told her she could just go. Grandmother moved out and didn't speak to anyone for a year. To this day she hasn't spoken to my mother, although she makes weak attempts through me.
This was my first attempt at the peacekeeper role. After my mom, sis, and GF moved to a new house my mom found a friend/bf. My mom had resigned from dating while we were small because her step father had been so awful. She didn't want to risk that for us. But we were grown now, it should have been ok. It wasn't. My sister was the youngest. It's always been my belief that she grew jealous, because she was a very jealous little sister. Manipulative, able to cry at will and smirk over my mother's comforting shoulder. I wasn't there....I was for the start of the party, but I left to join a friend's......there was a house party and there was a fight after I left. It was bad and it was stupid. My sister had plans for the next day, which required my mom's and bf's participation, from what I gather the party ended awkwardly. My sister and GF didn't feel they got enough attention and made things weird. Given that it was late, they were given a "let's see". My sister cried, sister's GF got mad and attacked mom's BF. Things got bad.
I heard about this in a round about way. I didn't hear from anyone for over a year. In that year I was paralyzed. I thought I was hated for my inaction. I didn't know what had happened. I spiraled into self destruction. Eventually, I got a letter from my mom and grandmother, separately, and renewed contact. My sister and her GF were now living off my grandmother. Occasionally they'd get jobs, but wouldn't hold them.
Fast forward almost a decade, my sister and her GF still lived off my grandmother. Only just this year did I convince my grandmother to stop payments. Lo and behold, they are fine. Able to afford everything they need and more. They were just taking her money.
Then, the other day, my step father was posting on Facebook. He frequently engages in needlessly risky behavior. He once stood in front of a feral pitbull rather than get in the car because "it's not going to attack me" even though it's growling. This is normal. He also can't hold down a job. He creates more conflict than there needs to be because in his mind everything works like in the movies. Confront the evil boss with her selfish behaviors and she's bound to feel bad and change her ways! And, y'know, not retaliate. So he's out of a job, again. My mom can't afford their house and dogs on her own. I've been lending her money in secret because "he can't know and you can't tell him"! He spends and spends. He isn't involved in finances because "it stresses him out so badly". Anytime things get too bad he threatens suicide. I get it, I know he had a very damaging childhood, but at SOME POINT we all have to take some responsibility. I say that as someone who has had severe depression for over 20 years.
Anyway, I called him out....I didn't breach any trust, I simply posted along the lines of "OMG!! Dangerous! Go be safe!!" and several of his friends joined in. It was that stupid. Now, understand, this one only part of a long line of needless stupid behavior that created risk for my mother...I lost my cool. I was mad. In my family, I've never been allowed to be mad, not even over something valid. To be mad was to be wrong. I have never been able to express anger in a healthy way and I was MAD. I was fed up with his foolish behavior as if the world worked like in movies. I was MAD that he'd stupidly risk my mom's wellbeing. I was MAD that they were laughing at me like it was a joke. We had a fight, us three.
My mom was the only stability I had. I was made to stand down.....again.....I'd stood up when my sister stole money, I'd stood up when my step father's family tried to control us, I'd stood up for my step father's self destructive behavior and each time...I was made to be wrong. "Don't interfere" was always what I was told. I feel like the sole voice of sanity in a tornado of crazy. I am always the bad guy, even though I never raised my voice until things were on the brink of collapse. I was always there to help, to comfort, to be the "safe place". But as soon as I take a stand I'm struck down......and I always apologize first. I did and I felt stupid for doing so. The fight is over and apologized for. Yet, nobody has contacted me....as if it were any other day. I feel so alone.
Despite what has been recommended to me....I have a very hard time making friends. That's a whole other story. I'm alone and now I feel like I have no family.