First, forget about your credit rating. That will come back once you're out of default and back on your feet.
Keep in mind that the write-off is considered taxable income, so you'll be owing the IRS and your State (if its an income tax state) money on that.
I don't think that you can ignore the second question. If you're going to end up robbing Peter to pay Paul, I don't see the point of trading an unsecured, dischargeable debt for another debt and a non-dischargeable IRS obligation. If you can't make payments on $17k, you can't make payments on $12k either. Note that when the IRS doesn't get paid, they seize assets from your accounts and garnish your wages, and charge hefty fees for the privilege.
If I were in your situation and had the ability to make payments, I would try to get written agreements from the unsecured creditors to do the following:
- Take you out of default status and get rid of penalty interest. (ie. start paying 15% instead of the 30% or more that you are paying now)
- Commit to making a specific payment.
- Freeze your credit limit to prevent the accrual of new fees.
You have a very short window to make this deal with BoA. If they are ready to cut you a 30% deal, the next step will be selling it to collections.
If I were unable to get those types of settlements or make the payments, I'd immediately start looking into bankruptcy and getting on with my life. A Chapter 13 bankruptcy will stop the accrual of interest and penalties, stop the collection calls and leave you with $0 debt in 36 months. If you go this route, try to keep one credit line that you've had for a few years (like a store credit card) open... this will make things easier later on.