Not long after Britney Spears married Kevin Federline in September of 2004, she wrote in one of her infamous Letters of Truth that motherhood is a lot like cooking -- "to be really good at it, you don't need instructions. You kind of just go on instinct and what feels right."

But on Tuesday, a judge confirmed the rock bottom-nearing tabloid topper's maternal instincts are lacking. After calling out her alleged "habitual, frequent and continuous" use of controlled substances and alcohol, he ordered her to submit to twice-weekly random drug tests and get a crash course in Parenting 101 in order to retain joint custody of Sean Preston, 2, and Jayden James, 1.

So, how did Britney react to the court's very serious smack-down, which came amid the hasty exit of both her lawyer and her manager?

If you guessed, "By spending a quiet night at home leafing through a stack of Dr. Spock books while sipping chamomile tea," you have grossly underestimated her capacity for self-sabotage and inability to understand cause and effect.

A few hours after the judge's ruling, TMZ.com caught up with the VMA-bombing, reality-rejecting starlet, 25, as she club-hopped in Los Angeles.

The usual swarm of paparazzi tracked her as she popped by hot spot Winston's, where she was seen with Avril Lavigne and pal Alli Sims, before moving on to Hyde Lounge.

"They kept bringing [Spears] shots and so they were drinking," a Hyde spy tells People. "She was dancing on the tables trying to be really sexy, even putting a black sock over her head as a hat, and putting on a show for everyone."

(Another of the mag's moles saw Brit in proximity to booze but didn't spot her drinking.)

The shutterbugs also fed the pitiable popster's craving for attention earlier in the day, when she stopped by a convenience store for an ice cream bar.

Photogs crowded around as Spears, sporting a pair of smart-girl glasses that failed to distract from the follicular horror on her head, daintily gobbled up the frozen treat (see said daintiness above).

Not surprisingly, her troubles are once again splashed across the cover of Us Weekly, which this week features a forlorn Sean Preston next to the gloomy headline, "Britney's Darkest Hour: Mommy's Crying."

According to the mag, Spears' all too apparent issues are taking a toll on her sons, who endured "heartbreaking" birthdays last week (even more worrying: the judge felt it necessary to forbid Spears and Federline from using "corporal punishment" with the tykes "and from allowing anyone else to do so").

"Dealing with the kids after they come back from Britney's is really hard on Kevin," maintains a K-Fed confidante. "It takes him three days to get them back on any type of schedule."

Spears, who once called motherhood "the closest thing to God" and proclaimed that "to be a really good mom ... your child needs to be your full time job," has also been ordered to spend eight hours a week meeting with a "parenting coach," something that will likely come as a relief to a chatty "family source."

"She loves her children so much, but it's like she's never been taught how to properly take care of them," the snitch posits to Us, adding that even when she holds her sons close, something is off. "She looks lifeless. It's like she doesn't understand the impact of being a mother."

Meanwhile, Spears' sad, destructive spiral was a topic of discussion this week during Justin Timberlake's sit-down with Oprah Winfrey, who asked for the skinny on his long-ago ex.

"I don't know, to be honest with you. I haven't spoken to her in years," sidestepped the chart-topper, who is currently dating the baggage-free Jessica Biel. "I mean, there's no ill will -- I have nothing but love for her. It's funny because we dated each other at a time ... wow, I haven't talked about this in a long time. It's interesting."

At the Big O's hard-to-refuse urging, Timberlake continued to reminisce, pointing out how young they were when they were together and reiterating how they no longer occupy the same orbit.

"We were teenagers, you know?" he says. "I think that's basically the best way to describe what happened to us. I think she's a great person, and I don't know her as well as I did."

At least Justin offers Britney some kind words to cling to -- and aspire to -- in this so-called "darkest hour": "What I do know about her is she has a huge heart, and she is a great person."

Next: Romance Report: Smooching, Snits and Splits