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Sorry for your situation...
You may file your tax return using Married Filing Separate filing status for 2008 and none of your husband's 2008 tax liability would affect you.
For previous years - as you signed joint tax returns - you are liable for the tax debt resulted by that tax returns.
Unfortunately - to satisfy tax debt from previous years - the IRS will garnish any tax refund from either of you.
However - you may qualify the Innocent Spouse Relief by filing the Request for Innocent Spouse Relief - Form 8857, if you meet certain conditions.
For additional information please refer to IRS Publication 971
and Innocent Spouse Questions & Answers - http://ftp.irs.gov/individuals/article/0,,id=109283,00.html
I suggest you to provide the information above to your tax preparer for considerations.
I wish you the best.