Question: The plot gives the impression that Ben was just using Sharon, but how? If he was always planning to murder his wife, then having a girlfriend would only add suspicion.
Answer: I don't think Ben always planned to murder his wife. He wanted to "have it all": stay married and carry on a relationship with Sharon (or someone else - he may have done this before). He lied to Sharon about his wife refusing to grant him a divorce. As Sharon's mother discovers, his wife knew nothing about the affair. She believed that she and Ben were happily married. Ben decided to kill her later, after she heard about Sharon (from Sharon's mother). She pointed out that he would not receive much money if they divorced. Presumably, he thought he could inherit money if she died.
Answer: She means she won't allow him to be the one to divorce her; she will contest it and won't sign the papers if he does file, and she will fight any grounds he attempts to file under.
raywest ★