A Nebraska high school teacher faces up to 20 years behind bars for having sex with a former student — because he rushed in too soon after she graduated, according to authorities. Sixth-grade teacher and wrestling coach Cody Pester, 26, started sending flirty texts to the 18-year-old girl on the day she graduated in May — with it turning sexual two months later, in July, according to police docs obtained by KOLN . The pair shared more than 13,000 often-romantic texts — and the teacher admitted