Truth About Soviet Music & Art?

I'm taking a 20th century music history course right now, and the professor is a strongly anticommunist progressive. Before he even started he claimed Stalin was unequivocally the worst person of the 20th century, if not all time. One of the most suspicious parts was when he told us about Prokofiev's statement against the capitalist world made upon his return to the USSR in 1936. He claimed that this was clearly forced out of him, despite having just told us how he had squandered 20 years trying and failing to find work abroad (one of the only things he did was a commission by a fruit company for a fruit-opera?). Additionally my teacher conceded that there is no record of Prokofiev's personal views from this time.

Then the is the whole Soviet Realism/Formalism thing. My teacher said these terms were intentionally ill-defined so that musicians/artists could be censored, imprisoned, or killed at the whim of Stalin. Again, I feel skeptical about how cartoonishly evil this description is.

So what is the history of music and art in the Soviet Union minus the Western propaganda? Is there a book or other resource I could use to learn about this?