They were pop music's Brangelina, when then-wholesome Britney Spears was inseparable from dashing 'N Sync frontman (and fellow former Mousketeer) Justin Timberlake. They even talked publicly of wedding bells! "Justin is everything, and what more could you want in a person?" Spears said. But the duo had a very public breakup in 2002, and now they're engaged – to other people.