It depends. Did you file a married filing joint return with her yet?
If not, then don't until her past due tax returns are filed. You can file married: filing jointly, after your wife files and pays (if there is a balance) her past due tax returns.
If you already filed a tax return with your new wife - you will want to learn more about: http://www.irs.gov/pub/irs-pdf/f8857.pdf - Form 8857 - Request for Innocent Spouse Relief
If the IRS finds your wife's social security number on a bank account, they may levy the funds, even if it is a joint bank account.
You may be an innocent spouse, but not until you can prove it.
For the exact tax code (laws) on Innocent Spouse - visit the irs.gov site and in the search box put in: innocent spouse. This will provide you with more detailed information.
Should you need help with past due tax returns - we are available. http://taxeswilltravel.com/pdr.htm