Couldn't sleep last night

So, I had a hard time sleeping last night because of the incident with Cian.  I feel like I really failed him.  I'm really upset because of it.  I'm trying to let it be a learning experience, but it's hard, I'm really mad at myself!  I know that nothing happened to him, but it could have.  Why wasn't I more watchful?  Why didn't I notice it sooner than I did?  I really do pay attention to my kids, I love them!  And I would never want anything bad to happen to them!  I'm sorry for what happened and I'm sorry Cian!  I love you!!!!