“I can’t imagine the difficulty in attending the same school from which your virtuous brother graduated.”

“I can’t imagine the difficulty in attending the same school from where your virtuous brother graduated.”

I agree that’s better — or, closer to your original:

“I can’t [cannot] imagine how difficult [hard] it would be to go the same school your virtuous brother graduated from.”

It is said that “A preposition is a bad thing to end a sentence with,” which is a sentence ending in a preposition. Ha ha ha. But Churchill (I think it was) spoofed that, something to the effect of, “A preposition at the end of a sentence is something up with which we will not put,” and of course it’s normal to say “…something we will not put up with.” Nowadays a preposition at the end of a sentence is frequently considered no problem, and it becomes an adverb, part of what they call the “phrasal verb. ” If you want to be a purist, then:

“I can’t imagine how difficult it would be to go the same school from which your virtuous brother graduated.”

No problem with the contraction can’t; often it better to reserve contractions for spoken rather than written English unless you are quoting someone directly, but in this case it may sound more natural. Cannot as a single word is better than two words, can not, in my opinion.

Someone else responded:

“If by ‘virtuosic’ you intended to use ‘virtuous’ as in moral excellence, I would change it to “having a model student brother”, because ‘virtuous brother’ could come across as snobbish or sneering.”

That may be true; you’d want to be careful. On the other hand it could be a sincere compliment and if so then you may have no fear in saying so outright. If you really do mean virtuosic in the sense of his being a virtuoso either musically or in some other field of accomplishment, then keep it instead of virtuous.

Then, another possibility:

“I can’t imagine how difficult it would be to go the same school from which your model student of a brother graduated.”

“even” is unnecessary, and is used only in informal speech.

“very virtuosic” is redundant. erase “very”.

“virtuosic” is an adjective. Where is the noun it is describing? “virtuoso” would also require a noun, as it can refer not only to a a master musician but also to a master of the arts or fine arts.

If by “virtuosic” you intended to use “virtuous” as in moral excellence, I would change it to “having a model student brother”, because “virtuous brother” could come across as snobbish or sneering.