You can only say that you "had" a clean background

not that you "have" a clean background. Get an expensive lawyer, you will need that. Don't lie, but don't plead guilty. If charges are filed, fight it hard then settle. If you are convicted and you have no green card, you can forget about the green card. Even if you have a green card, you may lose it. Abuse plus the lies may get yourself out of this country for good. Don't lie.