Poor Monty. Isn't it amazing how horrible an injury can look, and yet , will heal so beautifully. Hope your vet is right , and there will be no scar. Have had some very horrible injuries on my two, and have healed so well you'd be hard pressed to find them.
Lucky boy is getting excellent care and TLC. Best of luck to you during his healing period.
(isn't your initial response to something like that "OMG"! I know mine always is. Then it's "oh boy", because of the amount of time, money and care it will require. lol)
Be the kind of woman that when your feet hit the floor each morning the devil says, "Oh crap, she's up!".