Kathleen,
You are going to second guess yourself forever, its normal, I know I've been there, I still struggle with the "what ifs" Its better just to let go of it, like Don advised..You really will never know the answers so dont torture yourself trying to find them..
No matter what we do it wont bring our loved ones back, I dont know why we go through the "what ifs" I think its all part of the grieving process..
I'll keep you in my prayers that you may begin to find some peace with this, you have to or it will drive you crazy..With the holidays approaching it makes it so difficult, I hope thes days can pass gently for you.. Take care