My mom can't do it anymore... I feel she needs to give him up... help?

First off.. I am very proud of my mother for giving up her life to take care of my 43 year old severely retarded (disabled) brother. She has kept him since birth, and she is now 65. My brother can feed himself...and that's about it. She bathes him, cooks his food, and does his laundry. He does not use the bathroom ... he goes in his pants and in his bed.. all of which have to be cleaned multiple times per day. It seems like he enjoys making her life harder... example... making messes, getting into the fridge and dumping everything in the floor... all of this on a daily bases. My mom is 65 years old... she needs 2 knee replacements as she can hardly walk. She has went through the death of a grandson and cancer within the last 10 years. She owns a house that she can't afford the up keep and i'm afraid she is on the verge of loosing it. I'm really worried about her but she will not listen to reason. She has gave up her whole life to take care of my brother.... and its killing her. My other brothers and sisters have had to watch her slowly kill her self because of taking care of him. The human body is not meant to lift, and take care of 2 people for 43 years. I have done everything I can to try and convince her to put him in a home and come live with me. She could go see him every day.. take him places... spend as much time with him as she wants... but she just wouldn't have to worry about taking care of him. She could actually start living her life for a change.. and enjoy the time that she has left on this earth. It kills me to see what my brother has put her through over the years. I know its not his fault... but I can't help but despise him for it. My moms not happy with the way things are... i know she would be if she just took that step forward. I think about this all the time and I don't no what to do.... advice?