I know how you feel. You may or may not have seen the thread I posted when a little mini dobe ended up in my yard.

I did the same thing you did, took her in, crated her for the night, Sammy flipped out, hubby was furious. I wished I could have fostered her until we found her owners, but I had to think about my immediate family first. My poor Sammy had been in an altercation with a Pit Bull that I had tried to foster. He's now traumatized by other dogs. I couldn't do this to him again.

I thought I had done a good thing by taking her to a shelter, verifying that she was chipped and then releasing her so they could find her owners, only to find out that things could have still gone wrong. Her owners could have moved, not wanted her etc.

I think you did do the right thing. The shelter will call you if no one adopts him.

Keep your chin up! He's safer in the shelter than on the streets.