First, don't use actual names on this public forum- your business partner and her lawyers can read these posts too.
You need to check your LLC Operating Agreement and see which state's law governs - probably NY, if you're in NY.
See a NY lawyer ASAP. You've apparently waited some time, since you refer to registering a trademark, which takes 6 mos., and dissolving your LLC, so don't delay. You will probably want to sue her for breach of fiduciary duty, dissolution and accounting, and trademark infringement, among other things. You may also want to initiate a UDRP, or add that to a lawsuit, if her new domain name is confusingly similar to your LLC's TM. You may have waited too long to seek an injunction now, but this is one of the remedies you need to discuss with a NY litigator.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
Your question spans several areas of law (contracts, trademarks, & copyrights, among possible others) and cannot be answered based upon the limited information in your posting. You need to provide an attorney with all of the facts and supporting documents so that he or she can advise you properly. However, it it comes down to litigation with your former partner, it could get very expensive.
There are a variety of other causes of action that might apply to the situation in the State of New York, including both common-law and statutory causes of actioin.
I agree with Ms. Koslyn, however, that you should not be airing this dispute publicly on Avvo. You should gather your partnership agreement, the agreement you have referred to as your "operating agreement," "early versions of [your] trademark," materials demonstrating how long you have been in business, what you have manufactured or marketed, the states in which you have marketed and/or sold your products, information concerning the genesis of the designs your company has sold and any other information you believe bears on the matter and provide them to New York counsel to review. You should then have an in-person consultation with counsel to review your options.
Disclaimer: This answer does not establish an attorney-client relationship or constitiute legal advice. It is for general informational purposes only.