Yale Howarth, 15, was found at his Chirk home after staff at Ysgol Dinas Bran, Llangollen, quizzed him about a sexual encounter with another pupil.
An inquest said the teen was probably suffering from "extreme anxiety".
Mark Howarth, Yale's father, said schools should give better protection and support to pupils.
"The way our son was treated seems so heavy handed," said Mr Howarth.
"We should have been made aware of the situation so that we had some warning of Yale's state of mind on that day - at the very least we would have been able to check up on him."
The inquest at Ruthin heard evidence over three days about how the student was questioned when a girl pupil told staff that she may have had sex at a party, but had been too drunk to remember.
Council social services later reviewed the information and said no further action was required.
However, by this time, Yale had died in hospital.
Katie Carroll, from Irwin Mitchell solicitors, who represented the family, said: "It is crucial that lessons are learned from this to ensure that school children, who are clearly vulnerable and impressionable, are properly supported so as to eliminate the risk of similar incidents in the future."
Schools need to look again at how they tackle sensitive issues with pupils, says the family of a Denbighshire teenager who hanged himself.