Do you still want to breed you dog?

I made the mistake of letting my pit/lab mix out when she was in heat and my neighbors choco lab got her preggy....before that I didn't think much of breeding but with the troubles that came she is getting fixed next month. she had 9 beautiful pups, but there was something wrong and we don't know what, all 9 pups died within the first week, i didn't sleep for a week straight and it was just awful. she had to have an emergency c-section and after that she basically slept for 3 days, she is fine and back to normal, but the loss of those 9 pups is always on my mind and I am worried it is my fault, maybe I did not do everything I could have :-( before this I was actually thinking of breeding my chihuahua but it will never happen, my chi is also getting fixed next month and I pray that no one who breeds makes the mistakes i must have made and I hope that people who don't know what the hell they are doing to go and get their dogs fixed. I knew what i was doing with the birthing, but after this I will still never breed my dogs again