David, I'm sorry for your recent losses. I can't speak for Michael Osmond and would rather not speculate on the reasons for his actions.
Statistically, the suicide rate always seems to rise during especially stressful times. From my own personal experience, clinically depressed people grow numb, but can often "fake normalcy" through the daily grind of work and social interactions with friends & family. The depression sucks up all their spare energy, leaving them stuck in a rut and lacking the energy to make the changes to improve their situation. They can exist in this bleak, numbed state for years until some personal/professional/economical/security stressor tips their equilibrium past their ability to repress or disassociate... and they quickly decide to find a means to end their pain.
Sadly, psychiatrists have to watch their patients closely when they prescribe anti-depressant medication (or change medications or dosages). When a previously numbed-out patient receives some relief from medication, they unfortunately may use their new-found energy to end their pain.