My question is about my mom who has been depressed for over a year.  

She's an intense person who's been interested in social standing.  She lives at a high-end resort community in Scottsdale, Arizona with my dad (married for over 50 years).   They previously got along reasonably well because they led their own lives but now spend most of their time together and get on each other's nerves.  She complains that he has vision problems and is losing it a little mentally which is true. However, people who meet him generally find him pleasant and upbeat.  Behind closed doors, she is intense and critical, and wants to tell people how bad he's doing, which seems unproductive because people find him pleasant though realizing his vision is compromised and he is getting older. 

She says she wants her old life back but obviously we can't turn back the clock.  She now spends most of her time complaining about him, and saying how hard it is, when people would note, many women have lost their husbands and others have far worse health problems.  Her health seems reasonably good.  She is a "the glass is half empty and this is extremely serious, we need to so something about this immediately" type of person.  How should I approach this for her sake and equally important for my dad.