I was surprised the villain-like actions depicted in the drama were historical facts.
「ドラマで描かれてる悪役っぽい彼の行動が史実だと知り驚いた。」は英語で「I was surprised to learns that the man's villain-like behavior depicted in the drama is actually historical fact.」という表現が良いと思います。
描かれるーTo be depicted
悪役っぽいーVillain-like
行動ーBehavior・Actions
史実ーHistorical fact
アメリカ合衆国 
