Kevin Federline book excerpts about his ex-wife Britney Spears are making the rounds, and this latest story involves her sister Jamie Lynn Spears .

If you are not aware, the 47-year-old former back-up dancer and the 43-year-old “Toxic” singer got married in 2004 and ended up splitting up back in 2007. They share sons Sean Preston , 20, and Jayden James , 19.

In his memoir You Thought You Knew , Kevin claimed that her sister once wrote him a letter and he published the alleged contents.

After reportedly sending a holiday gift of a piano, one of Britney ‘s sons apparently wrote a thank you note.

Kevin alleges that Jamie Lynn wrote him to discuss the “well-mannered, appreciative, and kind boys.”

He alleges she wrote (via People ), “I’m sure my sister has ne

See Full Page