There are many facts that are not set forth in your posting that will bear on how your situation is handled at this point. Generally speaking, if you and your husband filed joint returns, you may be jointly and severally liable for the full amount of the tax liability [IRC Sec. 6013(d)(3)]. However, IRC Sec. 6015 provides three potential sources of relief from this liability for "innocent spouses." At this point, I don't have enough information to assess whether you would be a good candidate for such relief.
Additionally, there are timelines that must be followed for submitting and/or appealing your innocent spouse request. Please be mindful of any time limits that may apply.
Unfortunately, I don't believe I can answer all of your concerns in this Answer. However, feel free to contact me to discuss your situation, and I may be able to be of more assistance. Thanks.