Oh honey, what a terrible thing! Do NOT blame yourself though: there is no way you could have known this would happen.
OK, for physical wounds like this it would be best simply to keep him in isolation until he has recovered, keep his water quality absolutely PERFECT and salt the water gradually up to 0.3%. This is partly to help him osmoregulate at the wound sites and partly to help prevent any secondary infections. Hold it at that level until you see the wounds healing, then gradually reduce it back down. Do not add any other medications - they are not needed and will only increase his osmotic stress. Do not feed him for a couple of days - let him get over his initial shock and stress and find his way around the Q-tank. When you start feeding put small tiny bits of food on the bottom where he will come across them as he is nosing around, or see if he will accept morsels from your fingertips. Increase the tank temp a little if you can (up to mid-70's) to boost his metabolism and help him recover. He may be too stressed to survive if he is very tiny. If he does not make it, please do not blame yourself.
He will be very shocked and therefore his activity will probably be minimal for the next couple of days. Don't panic - give him time to adjust. Remember: fish are unable to feel deep pain, so he is not suffering as much as you think he might be. He probably looks worse than he feels. Even the missing eyes are not a complete disaster; once they have had a few days to adjust, blind goldfish can move around their tank and find food without any problems.
I certainly would not keep him in your main tank again however. Not just because of risk of further injury, but also because as a blind fish he will not be able to compete with the sighted fish for food and will miss out at dinner times.
Hope this helps. I wish I was there in person to help you through this.