You can't ask female students out to meet alone. If you prove that you value her, her behavior affects your family. We can't let her have such consciousness.

You can let your husband have time to invite this female classmate to your home for dinner. Be sure to stay at your home, then treat her well as the hostess, show her the love between your husband and wife, let her see that your's feelings are good, harmonious and happy, and let her back down. Be sure to invite others generously and don't have any dissatisfaction. If you are a happy person, such a villain will not look down on you. On the contrary, if you are sour, people can see at a glance that you can't catch your husband, and sooner or later she will try to take her away. Even if she is incapable, there is no guarantee that there will be a second or a third one. So you must be atmospheric. The more angry you are, the more anxious the other person is. Besides, you'd better leave her contact information and chat with her often, saying that her husband often tells you about her, and this classmate is very good and excellent, and so on. You should care about her out of the concern of an elder, contact her more, and it is best to put aside your husband and contact her alone slowly. If she gives up, you have nothing to worry about.