Tad, I am very sorry about your mother - 25 years has given tough but great advice. One thing i would add - I suspect that you are projecting your pain onto your wife.
When I suffered grievous loss during my xh's (continuing) MLC I totally irrationally blamed him. I could park my anger at the situation on someone else. knew it was crazy even while I was doing it.
It is very very hard to let go emotionally of someone you love, and it does sometimes feel like one loss after another. But life is full of loss as well as gain, and sometimes the balance seems in the wrong direction.
Tad, you have your kids, your health, and you are in the process of losing your mother. Gains and losses, the stuff of life, which makes us human. We will all lose our parents at some point, and it is hard.