I'm sorry you're going through this with your roo. I had a rooster a couple of years ago who partially ingested a string from a feed bag which wrapped around his tongue near the base (much like you would wrap a rubber band around your finger). By the time I found him the tongue was swollen, dry, half dead, and partially severed. I used surgical scissors to cut it the rest of the way off (this was also the only way to remove the string). The rooster immediately recovered and began eating and drinking with no problems for the rest of his life. He was perfectly able to swallow, crow, etc. I watched carefully for signs of infection but there were none so I didn't give him any antibiotics. If you're not comfortable doing it yourself I would have a veterinarian remove the dangling portion of the tongue and he should be fine. If you feel capable of doing it enlist a friend to help hold him and use a small, sharp pair of scissors (surgical or sewing). One quick snip and after that your roo should be fine. Even if he were to suffer complications at least you've given him a chance.
Best of luck- Leigh