How would I feel?

I have imagined the death of my son before today, and he is only just 10 months old. But I have imagined different ways he might be taken from this world because of something I did or didn't do. But I have never experienced a deep pain such as this. A dear friend has lost her son. It came at the hand of someone that she called for assistance. Her son was sick. I identify with what has happened in such a real way even though it is not the same. The many thoughts I have had about my son were things like being careless on the stairs and dropping him to his death. Or trying to do to much before waking up enough at his night time feedings and having something happen. Some of these are a bit far fetched, but given my treatment of him over the first 8 months, not totally unlikely. See, I have been very careless with him. From trying to do to much with him in my arms and dropping him to "forgetting" to properly and completely fasten him into his car seat. I have never really allowed myself to fully feel that until today. I began to cry as I put my young sweet son to sleep this morning. It hurts...really bad...