I fell asleep while I was ill next to my son, and the next morning I found him dead. Do I have to fast, or what?

Question:
She says: I was ill, and I had a small child of nursing age. I slept at night and put my son to sleep with me beside me, and he was in perfect health and well-being. But I, as I said, was feeling ill before I slept. I slept and put my son to sleep with me in the bed, as I said, and I did not realize what was happening, and I did not think of my son because I was ill, as I said, until my husband came after he had prayed the Friday prayer on the morning of that day and asked me about him: "Where is your son?" I said to him, "I do not know." So he went to the bed himself, lifted the blanket off him, and found that he had died under the blanket. Do I have to fast, Honorable Shaykh, or what is obligatory for me? May Allah reward you with good.

Answer:
If he died because of the blanket being placed over his face, and you are the one who placed this blanket over him, then you owe an expiation; because you are the cause of his death, so you owe an expiation by freeing a slave. If you cannot find one, then fast for two consecutive months; because you are the cause of his killing. Yes.