Your husband can contract to sell the home if he owns the home. Whether or not his name is on the mortgage has nothing to do with whether he owns the home. However, that raises the question of whether you're a co-owner and, if so, whether you signed. Again, that's a legal question.
However, don't start off by mucking around with whether you've got a binding contract and lawyers. Contact the Realtor. Say: "We want you to release us from the listing agreement." (Technically, the agreement is with the agent's broker.) If the agent (with the broker's agreement) agrees, then you're released. If the agent says no, then contact the agent's managing broker. Say: "We want you to release us from the listing agreement." The broker may agree. Or the broker may suggest you use someone else in his/her office. Or the broker may say no. If the broker says no, at that point, contact a lawyer.
Hope that helps.
If you have a signed listing agreement then it is a binding contract. You should look at what the cancellation paragraph states in your agreement. Unless it gives an immediate cancellation, then you are under obligation to fulfill the terms of the contract. However, if you are unhappy with your realtor, then you should contact him with your explanation and perhaps he will understand why you are not satisfied with him. If this does not help, you can always speak with the Broker of the real estate company.