There's a very simple rule of thumb that applies here:  if the police are threatening to charge you with a crime, you need to have a lawyer.  You can't get into the details of the case here, because it's not protected by attorney-client confidence, and without all the details, especially the difficult ones, a lawyer can't give you reliable advice.

The law lets you refuse to tell the police about private husband-wife conversations, as many times as they ask you about them, as long as the charges against your husband aren't for something he's said to have done to you, or the children of either of you, or you or your children's property.

If the police are asking about facts other than what your husband might have said, you're on thinner ice, and you really need to hire and talk to an attorney as soon as possible.