Complex sentence: The storyline ended in December 2008 when Whitney told a devastated Bianca all about the relationship and Bianca, realising this was abuse, called the police who arrested Tony, thus ending Coghill's three-month stint in the show.
Split into simpler sentences: The storyline ended in December 2008 when Whitney told Bianca, who then told the police. Tony was arrested, thus ending Coghill's three-month stint in the show.