I agree with several of the above posters that you probably can't get your soon to be ex wife from using your last name, unless you get her to agree not to as part of the divorce settlement. And that will likely cost you something.
Another matter though is whether you have trademark rights in the name of your business. If you do (and you should), then you would potentially be able to stop your soon to be ex from using your last name in a way that infringes your business's trademark rights -- for example if she tried to use it for her own business. This may not apply to your situation, but something to think about if she's planning to make commercial use of the name.