Is this my ex or a scammer? +6011xxxxxxxx threatening to leak fake nudes

A user received a threatening message on Telegram from an unknown number claiming to be their ex, who knew personal details like their nickname, dating period, and a friend's name. The sender threatened to leak a fake nude video, but the same number's WhatsApp owner denied the claims and threatened retaliation. The user is unsure if the sender is their ex or a scammer.