Timber, I'm so sorry! Suicide has got to be one of the hardest things the survivors can try and understand.
I know it's hard to talk about it, but it may help you (and your wife) to cope with the loss and make whatever sense you can of it.
I can't really say what those who chose suicide are thinking....I know that for some it's the end of painful life experiences that they just don't see any way out of and somehow they don't get the help they need.
It's very sad, no matter what the reason.