I have a mentally ill mother and a disabled brother. Some days I feel like I should pack up my family and move far away. She will not get help and because she is not a physical threat to herself or anyone else, I cannot make her get help. She gets angry if I leave my house without stopping to see her.
I can't even go to the gas station without her freaking out, leaving nasty messages, calling my friends and inlaws (to fight with them and accuse them of taking me from her), and drinking herself stupid. I am only in my twenties, but some days I feel very old and run down. My house is a mess, and I need to wash my car. I am just so worn out. I have no father to help me with this situation.
My brother is disabled and now suffers from anxiety. According to my mother this is due to my bringing my nine year old daughter to their house. She always wants me there, but my daughter upsets my brother (she wants to play video games with him when she is there).
She has always blamed me for her problems and is now blaming my daughter for my brother's problems. Sorry about the long vent, but God I needed it!!!

I know it sounds trite, but hang in there. My father moved in with me two years ago after living on the streets for a while. He did many of the same things you mention. I too have felt the urge to pack up and leave...

I know how it can age a person -- it did me. Do you have any one you can talk to? I started going to see a counselor, and it helped me out tremendously. Just being able to speak to a third party can work wonders.

Remember to take care of yourself first -- look out for YOU.... you are not to blame for your mother's or brother's problems.

ETA: I had to remove him from my house last year after he assaulted my son. He put himself back on the streets, but the VA arranged for him to be admitted to a veteran's home.  They are better able to take care of him.