It's ok to cry

Tonight at jammy time both kids freaked out on me. Ben was going on about something "scary" he saw in tv (which was not scary and they had both been retelling the story all afternoon over and over again and laughing) and Naomi suddenly clung to me and wouldn't say anything. This is the hard part. This is the part that I have been dreading. Naomi understands what is happening. She wrapped her little arms around my neck tightly and wouldn't let go, she curled up into my lap, I could hear her breathing sometimes soft sobs. I held her back as tightly and we just sat there, rocking back and forth and I tried to reassure her that everything would be ok, that it was ok to be sad, that I was sad too and that Steve and I would always love her, never leave her. She was quiet and subdued for the rest of the night, so unlike my kid that I am so worried and beyond upset. This is all my fault, how can I do this to her?