I am seeing my mother in a new light thats not flattering

I guess, in a way I am asking for advice.
But on the other hand, I am just venting.. Im not sure.

. I feel very strange about the way my mother is handling my younger brother who is 19. And a BIG part of me wants to step in. The other half of me wants to just sit , smile, and say it is ok when my mom does what she does.

When I was a teenager, apparently I was hard to handle. My mom, as most of you know, moved us out of state rather abruptly when i was 12.
Of course that pissed me off. BUT- it was a necessity. We had taken her then boyfriend to court for sexual abuse towards ME for 6 years.
He got off innocent because the jury claimed there wasn't enough evidence. Not even 24 hrs after that he was close to , or winning ( i don't know details) custody of my brother, his son.
So, on my 12 year old plate , there was alot to deal with. I started acting out, puberty squeezed my throat , and I hated moving from my friends and my life. Drugs were slowly becoming a 'leisure time' activity. So were cigarettes and sneaking out. I guess, no more then most other teens, I aws a handful.
My actions were met with anger, belts, slaps, yelling, etc. My mother tried putting me into counseling.... but that got me no where. This woman I would see would spend our hour talking about her diet, her dog, her son, her her her her.... >sigh<
My mom threw up her hands about me on more then one occasion claiming I was out of her control and there was nothing she could do.
Finally.. she told me that if i couldn't live by her rules, I had to go.
so , at 14 , I did. And she didn't stop me.
For over 4 years, i was gone. Sometimes I would call her , say hi... but that was it. I came home on my 17th birthday with my then boyfriend who was 34.
My mom said nothing, let him in the home, and put on her best June Clever smile and acted like there was absolutely nothing wrong. She always did this. Smile, ignore, and things go away. don't think about the situation because you will create more problems.
Her thought process was " I have done what I can, you are on your own. You will suffer the consequences of your own actions. Here.... have some apple pie. "
Im sure i was a handful, but at 14 I was thrown out. I used to think my mother was smart for this decision... now it is the opposite.

My brother is 19. Schitzophrenic and addicted to speed. He was a terror in the home. I saw alot of his behavior when I lived with my mother. He stole things, he snuck out and would be gone until the next morning, stole her car, her money, let people in her home who stole from her..
I can COMPLETELY understand being fed up with him.
She threw him out too.
He has never had any set rules, and discipline was " Oh son.. how can you do that to me... " Consequences, he was never taught. he never had to hold a job, never had to go to school. Any time he missed school it was " Oh son,you will pay for that decision one day or another...! You know better!"
Now during this time., she worked hard on getting him outside help. Tried big brothers big sisters, counselors, mentors, police, .. you name it, she has tapped that resource for help.
But she threw in the towel the minute he turned 18. Told him he was now and adult and had to do for himself.
He called me one time not too long ago and was crying scared. He didn't know what to do and was asking ME how to get along because " Mom threw you out too. How did you survive?"
I almost threw up his statement hit me like a rock. He was absolutely right.
My idea of my mother making a good decision to ' let me learn on my own' was just shattered. She did throw me out. She just let me go. Survive? F-k I didn't. I survived physically yes.. but mentally? Bullsht. I am a complete and total mess. And now, here he is at 19 living on the streets , in tents because he has no capacity to take care of himself and my mom has just thrown in the towel saying " I cant do it. I cant handle him, he wont listen"
The police called my mom from Ohio ( ! ) about a week ago saying they found my brother under a bridge with a few other homeless people and since he was on the missing persons list they wanted to tell her where he was. Long story short, he got a so called job with a traveling magazine company and either didn't report on time or didn't make his quota...
they left him there.
My mom? " Oh well, it hurts me , but he will learn. He is an adult now"
His young friend who lives in central texas talked to my mom and told her if he had to ( mind you he is 20 ) he would drive to ohio, pick him up and help get him on his feet. He has an apt, a job and a car. Has been doing really well for himself.
My mom said " He is a grown up young man . He can teach your brother what he needs to know about the world"

My insides screamed.. " WHat the hell are you talking about??? that is YOUR son. Why are YOU not going to get him? WHY are YOU not the one trying to teach him responsibility? Why are YOU throwing your hands in the air on this to the point where my brothers FRIENDS have to step in?

i can not believe this. I can not believe how my vision of my mom has changed since my brother called me. How angry I am that she threw her own kids out because she claimed she cant deal with them.
I look at my daughter and I cant not imagine doing that.
Now that I am a mother I play these scenarios out in my mind and I can not justify her behavior. But she can. With a smile and the " don't think about it, don't talk about it " mindset.

I almost don't want to talk to her ever again. But I feel I should. I feel I should point out to her what I THINK is wrong and how she should be chasing her son and DOING something for him.
But I don't think I should , or have the RIGHT, to do that.
Im not his mother, Im not his keeper. But I am his sister and I feel I could save him if only.. >sigh<