That's sad. I hope you feel better. I don't have any advice although I don't think that God is punishing you. What should you do? Take care of yourself and maybe see a therapist, doctor, or a minister of some sort. Times like that I usually read the book of Job, for some reason it's comforting all of the poetry in it. Those are just things that help me anyway.
I don't think that God is punishing you. I've thought that myself in my own life at times. I think sometimes God allows us to experience our weaknesses, knowing that they will bring troubles into our lives. But, I think that the weaknesses are there in order to help us to grow, and all of the while I believe His love is there and that He cares more about us than we can imagine. I am very sorry about your mom, that must be very scary. None of us live a moral enough life, and not everyone experiences the things you have, so I don't think that punishment is what is going on. It's hard for me to answer this because I have had similar guilt feelings in my life. Greater than those feelings though, is a belief that God is more love than condemnation.