GOLDEN, Colo. -- An Arvada woman who had sex and provided alcohol and drugs at teen parties she hosted pleaded guilty in Jefferson County Monday.

Silvia Johnson, 40, entered guilty pleas on two misdemeanor counts of sexual assault and nine felony counts of contributing to the delinquency of a minor.

Johnson hosted weekly parties at her home over the span of a year and admitted to having sexual contact with boys 15 to 17 years old, prosecutors said.

According to her arrest affidavit, Johnson said she also provided marijuana, methamphetamine, and alcohol to the teens because she wanted to be a "cool mom" and it made her feel like she was "one of the group." She said she was never popular in high school.

The parties took place at her home between October 2003 and October 2004 and involved boys from Arvada West High School.

One 16-year-old boy told police that Johnson performed oral sex on him on two occasions and that they had sex once. Another 16-year-old also told police that Johnson performed oral sex on him when she was engaging in sexual intercourse with another teen, according to the arrest affidavit.

The investigation began when one of the boys told his mother about what happened. Johnson was arrested in December 2004.

Johnson told 7NEWS earlier that she was going through a difficult period in her life and that she has apologized to the parents of the teens who are connected to the case.

Each sexual assault count carries up to two years in jail and a fine of $5,000, and each contributing count carries up to six years in prison and a $500,000 fine, according to Pam Russell, a spokeswoman for the district attorney's office.

Johnson remains free on bail until her sentencing on Sept. 26.