Things do vary by jurisdictions.
In CO, this would be attempted incest, by a person in a position of trust. The mother would be prosecuted, placed on the sex offender registry, do jail or prison time or have to complete a therapy program while on probation that is (arguably) worse than jail. (Probation set at 2-5 years, but is renewed automatically until the therapy program is completed to the satisfaction of the probation officer.)
Child protective services should be able to get you out of the situation, and with the national attention given to sex offenders, the likelihood that a DA wouldn't seek to pursue prosecution seems small.
ALso, there is the issue of mandatory reporting.
CPS is bound by law to report this incident to the authorities - mandatory reporting - and so criminal charges are imminent, I believe.
Historically, once a sex offender loses custody of a child, the probability of regaining custody (or even any significant parenting time) - it would be a tough and costly battle for the parent.
Hang in there, and confide in someone for support you can trust.

