I have a tendancy to question why I am going through this and why God would do this to me.
MC, I am sure you know this already, but here it is anyway. What happened to your M was not in God's plans, but despite them. He has given each of us free will, and unfortunately much of the ill that happens in our world is due entirely to the evil that His children do to others and to themselves in exercising that free will.
Your W walked away not because she was listening to God, but because she was not listening to Him.
Yes, I believe God has great plans for you too. If we continue to pray and listen to the Lord, He is able to turn the sinful actions of Mankind into good. Perhaps now He can mold you and the lives of your children for a greater purpose.