The TV host yesterday confessed to flirty exchanges with 23-year-old model Rhian Sugden after his secret was exposed by the press.
In an interview with The Sun, Kay confirmed that he has also sent sex texts to four other girls, but promised to ditch his habit for the sake of his family.
The father-of-two said: "Tess is extremely upset about this and we're working through it. But in some ways I'm glad this story has come out. It feels like a weight has been lifted off my shoulders.
"I knew it was getting silly. I'm never going to do it again and hopefully I can clear the slate clean and start again. I'm so sorry. I've been an idiot and I've let my family down."
He added: "I've been stupid and daft but I'm not a sex pest. I've only done this with four or five girls and I've known them all well - they've been friends or work colleagues. I know a single guy can get away with things like that but I'm married and I understand this is off limits."
Kay's text messages have been seen by The Sun but are deemed "too explicit" to print. The 35-year-old insists that he has not had sexual relations with any of the women.