First, let me say that I'm sorry to hear about your financial situation. Clearly you are going through a lot of issues with your husband, the IRS and other debts.
Now that you are separated from your husband you cannot do a joint resolution of the tax debt with him. You owe the tax debt 100% as does he. This is called joint and several liabilities. You'll have to work out a deal with the IRS and he'll have to do the same for his tax debt.
You may file Married Filing Separated for 2007 tax year but not Head of Household while you are still legally married.
An Offer in Compromise may be an option for getting rid of your tax liability. This is a fresh start where your tax obligation is wiped out for a one-time offer amount. The problem may be that you are not working. It's hard sometimes for the IRS to grant this wipe-out of the tax when you are in a temporary unemployment situation. However, it may work if you had low income for the years before you became unemployed.
Another option would be to get "currently not collectable" status. If you can prove to the IRS that you could not afford to make any payment to them on the IRS tax, then they may hold all collection action for one year through this process.
You can have less money withheld from your check by filing an IRS form W-4 and claiming more dependents. Make sure you don't over-do it though. The less you have taken out for taxes in your paycheck, the more you'll have to come up with when you do file your tax returns in April.
Freedom Tax Relief has the highest ratio of licensed agents (Attorneys or Enrolled Agents) per client of any national firm.
I hope the information provided helps you Find. Learn. Save.