Dawn Ward, star of reality series Real Housewives of Cheshire, was convicted of assaulting singer Sinitta on Friday.
The 43-year-old, married to former footballer Ashley Ward, was found guilty of one count of common assault following a two-day hearing in London.
In April 2015, the pair had arranged a lunch meet at a Belgravia restaurant to try to clear the air between them following gossip about a friend's affair.
During the meeting, Ward shoved and threw a napkin at a "shocked" and "humiliated" Sinitta, Westminster Magistrates' Court heard.
Ward was warned by District Judge Elizabeth Roscoe that she would be bound over in the sum of £500 for three months and ordered to keep the peace and be of good behaviour.
No costs were awarded.
The judge said: "I am going to deal with it quite unusually because I think this quite frankly is, to use an old-fashioned phrase, 'a storm in a teacup'".
She added that the fact the court "has had to spend two days (hearing this case) and have a (police) officer here for two days is a nonsense".