I have worked in the student loan field. First thing you need to do is contact your loan servicer immediately and work with them about your potential default situation. (Even if you have already gone into default, you can get out of default by getting on a loan rehabilitation program and making 12 consecutive, on-time monthly payments under that plan, so all is not lost.)

Also, look into an income-based repayment plan. These work basically the way you might think they do, in that your payment is based on a percentage of your income. One nice thing about it is that if your income is low enough, your payment can end up being zero. The kicker on the income-based payment plan is that if you make payments for 25 years, the loans go away, regardless of the amount you've payed on them. If you're in for $100K+ and don't have a commensurate income, this can give you back some of your financial life (your debt-to-income ratio is going to be screwed up for the next 25 years, but at least you'll be able to make your loan payments on time).

Bottom line, contact your loan servicer IMMEDIATELY and ask about payment plans that are tied to your actual income. It's your best option. If you just let it go, you'll never see the end of it, as they can attach your bank account, take your tax refund from you, and probably worse.