Dad has COPD and mom gets upset because he can't do much anymore. An argument breaks out almost daily. Now dad acts depressed. What can I do about it?

Your mom's doctor or some third party must explain to your mom that she is being unrealistic. His depression sounds situational and made worse by his wife's disbelief and daily arguments. She must be a very selfish person who only cares about what her husband can do for her and can't see anything else or she is in extreme denial. It would be nice if the doctors could explain what is going on so that you don't have to be stuck as the only child between mom and dad in an emotional triangle which has no winners.