"I continued to protect her until just recently," the 31-year-old wrote, "when she decided I didn't need protecting and threw me to the proverbial media wolves." 

In response to "outrageous claims" in the book, Britney's lawyer filed a cease and desist letter to the actress, writing, "Although Britney has not read and does not intend to read your book, she and millions of her fans were shocked to see how you have exploited her for monetary gain. She will not tolerate it, nor should she." 

And, in her own Instagram post, Britney slammed her younger sister for allegedly continuing to try to profit from her success. 

"I wish you would take a lie detector test so all these masses of people see you're lying through your teeth about me !!!!" Britney wrote at the time. "I wish the almighty, Lord would could come down and show this whole world that you're lying and making money off of me !!!! You are scum, Jamie Lynn."