Generally, she can use anyone she wishes to represent her, even a family member. You must find legal counsel in your area, experienced in matrimonial matters, to represent you. Do not leave the house until all issues are resolved and do not go it alone!
I strongly suggest you try to mediate your separation with an experienced matrimonial attorney-mediator.
If you are living in the NYC metro area, give me a call at 212-370-1660 to arrange for a meeting to discuss the matter at greater length.
Leonard M. Weiner, Esq./Divorce Solutions