Honestly even if he ends up being permanently lame that's not necessarily a reason to put him down. Many horses have lameness issues and still end up living happy lives as a pasture pet, but you have to weigh how good his quality of life would be if that happened. I hope that he heals up fine though. Horses do have an amazing ability to heal. I had a Thoroughbred mare who tore her superficial flexor tendon (the big one that runs down the back of the lower front leg) so badly that it was hanging by a thread, and the vet gave her a 90% chance of being lame the rest of her life, but after 6 months, she healed perfectly, and a few months after that, she was jumping 5' courses again. Just think lots of good thoughts. Hugs for you and him as well.
So yeah, putting him down is probably not going to happen. =] Got back from the vet today, and there is no abcess, so the vet put something on his hoof that is going to help his hoof grow out. It will fall off in thirty days, and then we are going to lace his hoof together or something(lol. I don't really pay attention to my uncle and the vet when they chatter).
I was watching him walk today, and wow, he is barely limping. Mind you, he still takes a long time to get around, but whatever the vet put on his hoof helped. We are also putting petemoss in his stall(for some reason? Again. I don't pay attention), and he is on a supplement to help his hoof, and everything is looking good.
Now, we have to just be patient and give him all the loving and support we can, and get him back healthy.