You should review your specific facts with your attorney before taking any action.
The IRS likely would likely argue that "income in excess of $150,000 a year" is hard not to notice. That is, you should have known that there was some income not being reported. With you being "a stay at home Mom", where did you and your husband get the money to live the lifestyle you two led?
Because you signed the tax return, the IRS may very well want to hold you responsible for the unreported income, taxes, and penalties.
Whether the fact that "he would physically and verbally would intimidate [you] into signing them" would offer you any mitigation factor depends on all the facts.
What you likely should not do is report the alleged fraud to the IRS without first considering how you may also become incriminated.
You should review your specific facts with your attorney to find out what legal options may be available to you.
I would be sure to talk to a tax attorney. The question is, has the IRS come back to look at them, and found a deficiency? Or are you just trying to cover yourself just in case? If there is a deficiency, then Innocent Spouse and the related options are a possibility. If not, then you should talk not only to a tax attorney, but one who is knowledgeable with criminal Tax Defense. (Not just criminal defense, but criminal tax defense, there is a difference)
You should immediately see an attorney familiar with these matters to protect your rights.
Any individual seeking legal advice for their own situation should retain their own legal counsel as this response provides information that is general in nature and not specific to any person's unique situation. Circular 230 Disclaimer - Advice given in this response cannot be used to eliminate penalties with the IRS or any other governmental agency.