Myleene Klass has received a public dressing down from the headteacher at her daughter's school after shaming two mums who asked for £10 donations to buy their children a Kindle and a desk.
The radio presenter shared the mothers' email with her 500,000 social media followers and described them as 'bonkers'.
But she was rounded on by other mums in the school playground, who accused the mum-of-two of orchestrating a 'cheap publicity stunt'.
Now, the head of the £5,000-a-term north London independent school where Myleene sends her seven-year-old daughter Ava has reprimanded the star in a newsletter to all parents.
She wrote: "As my granny would've said, if you can't tweet anything nice, don't tweet anything at all."
In the newsletter, which discussed 'fundamental British values' (FBV), the head made it clear she did not approve of Klass's actions.
She wrote that 'our pupils are young, receptive, and eager to learn', but said it was much more difficult to teach them when they 'observe attitudes and behaviours that fly in the face of our values'.
The head wrote: "It was not my intention to use the [newsletter] this week as a soap box, but here it comes ... how I wish I could focus on your daughters' education and not on responding to media trivia.
"How many times this week have I been asked to comment/act/intervene/reprimand/ ... do something! Mutual respect and tolerance. FBV. We actively promote them – do you?
"I needed to get that off my chest. Now, on with the week's round up of [school] news. No more parking on zig zags. No more blocking in the neighbours. No more unicorns. And as my granny would've said, if you can't tweet anything nice, don't tweet anything at all."
In a column for the Daily Telegraph on Saturday, HearSay singer Myleene admitted that the emails were a year old.
She said she thought her response was 'funny' and had no idea of the backlash it would cause.
She wrote: "Family, for me, comes first – not money or showmanship. I know I am in a privileged position compared to many, but I live in the real world and have countless friends who wouldn't be able to put that sort of donation into a schoolbag.
"But this isn't just about money; it's also about social responsibility. You have to think about where this sort of behaviour is taking us next. If this is happening at the age of seven, what are our children going to expect at the age of 10?
"I'm not sure if speaking out makes me courageous or an idiot."
THE EMAILS THAT CAUSED ALL THE CONTROVERSY...
Myleene, who is also mum to three-year-old Hero, posted a picture of the mums' message (after changing all names), which stated: