Complex sentence: Short (an aspiring singer) went to work as Mr. Spector's assistant, Michelle Blain's assistant, and by the time they were married (Sept 2006), she was running his business.
Split into simpler sentences: Short (an aspiring singer) went to work for Mr. Spector's personal assistant, Michelle Blain as her assistant. By the time they were married (Sept 2006), she was running his business.