You could be charged with a felony, but often they offer to settle for repayment of the benefits. But, a zealous prosecutor could easily convict you of a crime here, so step lightly. Ultimately, do not incriminate yourself. Contacting the unemployment board to do the right thing would be a mistake because you could end up losing your ability to receive unemployment benefits in the future.
Before you do anything, you should consult privetly with a criminal defense attorney. Sometimes they can arrange a plea deal before you are actually charged with these federal crimes. Thank you and I wish you the best of luck!
As Tom mentioned, the likely result is that you will incur penalties and fees for fraudulent collection of unemployment. This is not dischargeable in bankruptcy, either. You can also be charged criminally, although they will be more merciful if you do pay it back in full, and if you are proactive and pay it without any complaint against you they are not likely to do so.
Clark County, Nevada practitioner.