He is now in pain but he will feel better in time - even if he loses his lower beak which I hope he doesn't but going by what your vet told you, it is the most likely scenario. But, even if he does (and let's hope he doesn't!), it's not the end of the world. Animals are amazing when it comes to handicaps, they never dwell on them, they are never discouraged or even feel bad about their limitations, they just keep on living for the day, trying and adjusting as they go on.
If I were you, I would put his cage in a quiet place with a heating pad under it and a towel or something covering all sides but the front. Parrots are prey animals and they feel very vulnerable (which translates into stress) when they are wounded/sick and exposed so they prefer to hide and allowing them to do it helps with their recovery. I would also start him on a soft diet because, if he loses his beak, he will have to eat it for the rest of his life.
I also had a lovie that had half her lower beak. It had been torn off by also an Amazon and it never grew back whole but she managed VERY well with just a half of it. And I have a Quaker whose upper beak was torn from the side and it took a long time because the trauma had displaced it so her lower beak grew more on one side than the other and kept on pushing it more to the side but I trimmed it and trimmed it constantly to encourage it to grow straight and that helped a lot. It's not straight but you can hardly notice it and she even eats seeds with it (they need to be small because she can't open it all the way but she doesn't mind).
i feel so bad for him what happened
