“To a convict born” Gossip Girl star LEIGHTON MEESTER’s blistering war with her ex-con mom has taken an ugly turn as legal war and shocking allegations ensue!

In a high profile court room melee the "Gossip Girl" star has filed a $3 million countersuit against the brunette beauty.

As The ENQUIRER first reported Leighton’s mom gave birth to her now-famous daughter while serving time behind bars on a drug rap.

Now Constance Meester claims her famous daughter reneged on an oral agreement to pay her $10,000 a month, cancelled her health insurance and allegedly assaulted her in December by "throwing her to the ground and repeatedly hitting her with a bottle," the suit states.

The Meester mom, 54, who gave birth to Leighton Meester in a halfway house while serving a federal sentence for drug smuggling says Leighton's "malicious" neglect has left her "destitute" as she cares for Leighton’s sick younger brother.

Constance alleges in the suit filed that her house fell into foreclosure and she also needs $5,000 a month to treat her Hepatitis C.

Constance Meester claims she deserves millions in cash because she "sacrificed her happiness" to further her daughter's career, the lawsuit alleges.

Meanwhile, Leighton Meester, 25, knowing of her mother’s legal rage filed her own suit Friday in anticipation of her own mother’s shocking claims.

Leighton’ suit alleges that she sent $7,500 a month to support her ailing younger brother Alexander and charges her ex-con mom used the money for plastic surgery, Botox and hair extensions.

"Leighton had no obligation to provide this financial assistance to Constance and Lex, but she voluntarily did so out of love and concern for Lex's well being," the "Gossip Girl" star’s complaint states.

Leighton Meester's suit charges her mom, Constance, is a deadbeat who refuses to work and is an addict who swiped her son’s painkillers after he underwent brain surgery.

The actress is asking a judge to confirm there's no financial contract with her mother. Leighton’s attorneys said the star will continue to pay for her brother's medical insurance and private school tuition but won’t give her mom one red cent.