(((hugs)))
Welcome, FM. Glad to see that you will be coming back. There are so many here on SR to offer support and wisdom. I'm sorry to hear about the struggles you and your family have been facing.
It seems from your post that your brother's problems began after the accident.....is that right? Just wondering if there was any indication of addiction/alcoholism before that.
I ask because depending on the answer, there may be resources available. Honestly, I don't know exactly what resources are out there.....only that it might be worth looking into. My grandfather (we think he was schizophrenic even though he was never formally diagnosed) was totally incapable of taking care of himself. My father had to file for conservatorship (sp?) because he was a danger to himself, meaning that my dad could make legal decisions for him. It took a long time, but finally my dad was able to help him.
Ultimately though, you and your mother may need to start thinking about the idea that, as much as you love him, he has to want help before anything can be done. Try to focus on what you can do today for yourselves. I wish you the best in dealing with this.