On Tuesday, Glanville posted on Twitter: "Im not taking cheap shots at my ex in my new book cuz its all true,&now mr fancy new cars&house man is asking ME for child support!"
Glanville, 41, and her ex have two sons, Mason, 10, and Jake, 6.
A rep for Cibrian says in a statement to PEOPLE, "There is no truth to the claims that Eddie has requested child support from Brandi now, nor will he ever request child support from his ex-wife. The notion is preposterous. This is yet another ploy for self-promotion."
The Real Housewives of Beverly Hills star divorced Cibrian in 2010; he married LeAnn Rimes in 2011.
A source close to the situation says, "Now that Brandi is making money and is successful, Eddie is backtracking on a prior agreement they had regarding child support payments. He's asking for money back from her, over $100,000, saying he overpaid. But he's asking for more than he's paid her in the first place!"