Rachel Duncan was in federal court in Columbia Wednesday to enter the plea to wire fraud and tax evasion charges.
Prosecutors said they found sexually-oriented photos of Duncan on Tom Sponseller's computer. But prosecutors said there is no indication he received any of the $480,000.
She faces up to 23 years in prison and $350,000 in fines. Sentencing is expected in June.
Prosecutors say she used much of the money for online gambling.
Sponseller killed himself in February. Police say he left a suicide note detailing his despair over Duncan's apparent misdeeds.