I know how hard that can be. I have abunch of stray cats that live in our 2 sheds in the backyard. I feed them, leave out water, and have bedding there that i was everyday for them. I feel like i am there owner when im actually not! My neighbour used to trap them in our shed and take them to a shelter as well. You definitly did not fail them, I wish there were no cats that had to experience been a stray and i am sure alll those kitties and there mom loved you endlessly for helping them out! You will always be upset abut the others kitties but be happy you just rescued alife!