As concern mounts for the welfare of his two children with now ex-wife Britney Spears, Kevin Federline is preparing to sue the troubled songstress for full custody of the couple’s toddler boys. A hearing has been set for August 14th.

“The lawyer Mark Vincent Kaplan is going to claim that Britney failed to meet any of the benchmarks, including attending Alcoholics Anonymous, after finishing her 28-day stint in rehab earlier this year,” explains a tab insider.

“People are telling me I should take the kids away from her” K-Fed confessed to a source “I’m glad the world is finally giving me the benefit of the doubt that I’m actually a good father.”

“She smokes like a chimney in front of them,” says a tattler.

“She’ll actually turn to Sean and say, ‘Baby, where are Mama’s lollipops?’

“It’s tragic what these boys are exposed to on a daily basis.Kids thrive on routine and the feeling of safety, and Sean and Jayden have neither.”

“She has a short attention span, and that applies to caring for her kids. Jayden is at a fussy stage, and when he starts crying, Brit hands the baby to a bodyguard to calm him down.

“When she needs a break, she gives her boys to the nearest person — even shopgirls at clothing stores!”

“He’s having dental problems because Britney just shoves a bottle of juice in his mouth all the time to stop him from crying,” a family insider tells Us.

Another source says that, in April, Spears “asked an L.A. dentist if he would whiten her kid’s teeth!” The dentist refused.

Those close to the singer aren’t surprised that Spears’ lifestyle is wreaking havoc on her children’s teeth.

A Spears pal says the star “feeds them total crap like Doritos and soda,” and even gives the toddlers chewing gum.

“She fed Sean ice cream before bed because the cold would make him sleepy,” says the source who logged time in the singer’s home.