You are most likely liable: 1) your husband should have simply not signed if he needed to discuss it first or get your approval--once someone (or an agent of a company) signs a contract, they are held to it; 2) if, as I suspect, to a reasonable outside person, you husband (husband of the owner) would seem to have the authority to enter into the contract, they may rely on that apparent authority; 3) thinking it was a proposal is no defense--the law presumes (and requires) that people read and understand what they sign.