Complex sentence: Libba is friends with many young adult authors such as John Green and Maureen Johnson, and with fellow YA fantasy authors Holly Black and Cassandra Clare, all of whom are represented by Bray's husband, a literary agent.
Split into simpler sentences: Libba is friends with many young adult authors such as John Green and Maureen Johnson. Bray is also good friends with fellow YA fantasy authors Holly Black and Cassandra Clare; all of them are represented by Bray's husband, a literary agent.