Note that there isn't always an interview. If you believe the marriage is not bona fide, you need to inform USCIS immediately. If you pretend that this is a bona fide marriage, not only could he be in trouble, so could you. Did you already fill out an I-864? You know you will be on the hook for that as well.

Hopefully, you have an immigration attorney already. If not, you need one. You need to get him working on all this.