Simplify the following text for a Grade 5 native English-speaking person.
Original: Previously engaged to actress Shar Jackson , Federline is best known for his two-year marriage to pop singer Britney Spears .
Simplified: He is famous for being the former husband of pop singer Britney Spears . Federline has 4 kids , 2 with actress Shar Jackson and 2 with Spears .