Baby girl fell off the couch

I(34m), was alone last night with my six month old baby while my wife (30f) was hosting a baby shower for a friend. At one point my little girls bottle ran dry and she wanted more. The floor was cluttered so I made the mistake of putting her on the couch and making a little blanket barrier while I went and refilled her bottle. After all, it's only 30 seconds. Nothing could happen... Right? Wrong.

My poor little baby rolled over and fell face first onto the hardwood. I heard the "thud!" followed by a blood curdling scream. I sprinted back to the couch and found her face down on the floor, screaming and flailing her little arms and legs. I scooped her up and cradled her and noticed her nose was bleeding. Immediately my heart sank and I started crying uncontrollably while trying to stop the bleeding and calm her down. We both cried for around 20 minutes. The bleeding stopped easily and she has since recovered perfectly fine. I've been monitoring her very closely for any signs of trauma but everything seems okay, except for my heart and my conscience.

I can't believe I let something like this happen. I keep imagining the tragedy it could have been if she hit the soft part of her head. I feel like a failure of a father. I can't get it out of my head. My baby could have died. I failed her completely.

Let this be a warning to any new parents: never leave your babies unattended, even in the most mundane scenario.