I'm scared to go to sleep because I almost killed my daughter?

I am absolutely terrified to go to sleep again. I haven't gotten a good night's sleep in a week. Last Monday I was home alone with my 1 year old daughter and she was playing with her little bouncy ball and like an idiot I left the back door open which is about 4 feet from our pool. The phone rang and it was my mom and I was drawed into this conversation with her while my daughter was running around with her toy. Then there was this plop noise and I turned around for just a second and I saw water splashing and her toy in the pool. I rushed over to save her and she was sinking to the bottom absolutely terrified. Ever since then, I've been an emotional wreck. I haven't told anyone in fear of being labeled the worse mother ever which is how I feel and I can't let my daughter out of my sight without having a panic attack. My husband keeps asking what's wrong with me but I just can't tell him. She is his world and if something had happened to her, he would forever hate me. Every time I close my eyes I see her looking frightened in our pool and now going around water makes me sick. I have been having terrible dreams every night for a week about my baby dying reaching out for me and me not getting there in time. I can't sleep. I spent all of last night pacing my living room, holding my daughter's blanket. I can't take this anymore. I'm at the end of my rope, and I don't know what to do. Can anybody help me?