Sid was heavily into drugs by the time he left school.

【heavily】锡德毕业时已经沉迷于毒品。

By the way, a random aside here, it later transpired that this suitor was heavily into sadomasochism, so maybe she kind of dodged a bullet there maybe?

后来发现这个追求者是重度施虐狂，所以也许实际上是躲过了一劫？