You have the right to expect the undivided loyalty of your lawyer and his or her law firm.
If your lawyer works for a law firm that is, at the same time, doing legal work for the other side, you should have been told about it at the outset, as there is at least an apparent "conflict of interest". While it may be possible to waive a conflict of interest, you have to be made aware of it to waive the conflict.
There are some specific steps you can take against what appears to be unethical practitioner:
Fire her immediately;
File a complaint with your state bar disciplinary committee. They will examine charges of professional misconduct. If there was improper conduct, ask that they force her to return your fee.
File a copy with the divorce court. Tell them that your divorce lawyer represented your husband on another matter in the past, did not disclose this fact to you or give you a chance to consult other counsel, and now appears to be trying to protect his interests at the expense of your own.