Britney Spears launches new attack on sister: 'You thought I wasn't cool'

Britney Spears is calling out sister Jamie Lynn Spears for being insensitive to her back in the days.

In her new post, the 40-year-old wrote: "You selfish little brat! Saying how weird and dumb it was that I bought a house for Mamma!

"She was so proud and you told that interview girl that it was just weird.

"…Why did you say that?"

She went on to call Jamie Lynn "f**king hateful."

Britney continued: "And the topic about the knife, which is ironically the only lie you’ve ever told in your whole life, why is that conversation 20 minutes?

"And [it was] the most degrading to me… OH BUT you don’t want to keep talking about it because you don’t want to HURT ANYBODY’S feelings."

The pop star later went on to add how Jamie Lynn dyed her hair life, Christina Aguilera, dubbing her insensitive after Justin Timberlake breakup.

"When I came home you and your little friends all thought I wasn't cool ... You felt bad for me in the breakup ... HELL NO you didn't !!! You and your friends all dyed your hair like Christina Aguilera and you no longer would play with me anymore !!!"