Leighton Meester, 25, known for her role as Blair Waldorf on the CW’s ‘Gossip Girl,’ has sued her mom for mishandling money. It’s unclear how much Meester is seeking.

Her mother, Constance, has allegedly been spending money originally meant for Meester’s brother, Lex, and his medical issues. The suit alleges Constance spent the $7,500 a month on cosmetic procedures and other expenses.

“This whole thing’s been really tough on Leighton,” a source told PEOPLE. “Her only concern has always been taking care of her brother. Leighton’s really close with her brother and her dad — her parents are divorced.”

According to Meester, her mother also threatened to sue the actress for $3 million if she did not give her $10,000 a month.

This isn’t the first time the ‘Gossip Girl’s’ mother has been in trouble with the law. In the 1980s, she was convicted for lending a helping hand to a drug ring and smuggling marijuana from Jamaica to the U.S. She then gave birth to Meester in a Texas halfway house.

[PEOPLE]