A MOTHER in the middle of a custody dispute has been caught boasting on her Facebook page how she thought about ripping her husband off for another $20,000.

"Felt like being a smart arse," she wrote, signing off "Bwahahaha lol."

Lawyers are now advising their clients locked in Family Court fights to take down their Facebook pages as the networking site has become both the latest weapon and target for warring spouses.

In one case a woman discovered her husband was a bigamist when she was tipped off to look at wedding photographs of him with another bride on the other woman's Facebook page.

In another case a husband discovered he had been set up by his wife with a woman he thought he met on an internet site. He discovered the woman was a "friend" on his wife's Facebook page.

"I tell my clients just don't bloody do it, don't be silly" family law expert Michael Taussig QC said.

The woman who boasted she had thought about dragging out the Family Court case to cost her ex-husband an extra $20,000 in legal bills found it backfired on her.

Justice James Barry granted custody of the two children, aged nine and eight, to their father with the mother getting visiting rights.

He then ordered the mother to pay $15,000 of her ex-husband's estimated $35,000 legal bill, saying the mother's behaviour had been the "stuff of nightmares".

She had already strung the case out by falsely claiming her ex-husband had been sexually assaulting their children after one judgment went against her.

Then she falsely claimed the father's new wife had been assaulting them.

"The mother has over the years attempted to manipulate the court system," Justice Barry said.