The first thing you need to realize--and it's absolutely critical--is that student loan debt is not like traditional debt. There are a lot of different payment options, a lot of strategies to consider, and a wealth of other things that simply don't apply to traditional debt.
The second thing you need to realize is that the members on this forum are (a) usually very debt averse and (b) don't know the ins and outs of the student loan system. James (one of the above posters) is a great contributor on these forums, but for the reasons below, I strongly disagree with his post.
I think it's absolutely necessary that you read every post in this thread (copy paste the link if the hyperlink isn't working):
http://forum.mrmoneymustache.com/ask-a-mustachian/gaming-repaye-and-the-student-loan-system-($148-000-debt)-to-achieve-fire-at-45/
Once you've read that entire thread (seriously, stop reading this post until you've read every post in that thread), let's get to your specific situation.
(1) The Department of Education just expanded PAYE to include borrowers who borrowed before 2007--this is called Revised PAYE, or REPAYE for short. This means that you can (and probably should) sign up for REPAYE. This will reduce your payment from 15% of AGI to 10% of AGI. Your years enrolled in IBR will roll over to REPAYE.
(2) Focus on reducing AGI (as explained in my post) and pay as little as humanly possible towards your loans. Have your husband max 401k, Traditional IRA, etc. as much as possible so you pay as little towards your loans as possible. Lower AGI = lower payments, with the side benefit of increasing your savings rate.
Note--never, ever, forego income opportunities. Always look to increase income. But simultaneously get creative with tax laws (as many posters on this forum do) to keep your AGI (and thus your student loan payments) to a minimum.
(3) Figure out some way to save for the tax liability. I (and a lot of others who follow student loan legislation carefully) are quite confident that the tax liability will eventually be removed, but as it stands now, you need to plan for that. I would set aside $5,000 a year in a money market account and let it ride for 19 years, then use that for the tax liability and the rest can roll over to your kid's college expenses.
Now let's build on this and get to some numbers--the fun part.
Option A -- Ride REPAYE All 25 Years: You already have six years of payments under your belt. 72 months x $500 = $36,000. If you sign up with REPAYE your payment should go down. And if you become smarter with reducing your AGI, your payment should go down as well. All in all I think it's fair to say your payment will initially go down when you sign up for REPAYE, it will go down further when you get your AGI down, and it will then go up once income increases. So I think it's fair to say that your payment will average about $500/month over the next 19 years.
$36,000 already paid + (19 years x $500/month) = $150,000 in payments towards the loan.
These payments will not have covered the interest, though, and your loan will likely have a balance close to $500,000. Now you have to pay 38% tax liability on that, or $190,000.
That comes to a total of $340,000 total paid toward this loan.
Option B -- Aggressively Pay Down Loans: The other option, and the one I assume will be recommended, is a bunch of "your debt is an emergency, pay it off ASAP."
Well, your loan has ballooned to $250,000. It's tough to make this calculation because I don't know your interest rates, but I think it would take about 10 years of payments at $2,800/month to pay that off in full.
Guess what? 10 years x $2,800/month = $336,000 total paid towards the loans. That number would be higher if your interest rates are above 7 or 8 percent.
Now, there's obviously lots of variables with both A and B. For instance, increase average monthly REPAYE payments to $750/month--that brings total paid in monthly payments to $171,000...but your tax liability would then be lower. In summary, I think you would probably pay between $340k and $375k towards your loans if you did REPAYE.
Put another way, I'm pretty confident you will pay less towards your loans if you opt with REPAYE. Furthermore, even if you technically pay more, think about the time value of money (i.e., a gallon of milk cost less in 1995 than it does in 2016). Sending in a $500/month payment won't be that big of a deal 15 years from now because $500 will be worth less than it is today.
Note that this is the same logic used by people who argue that you shouldn't pay off your mortgage. "Hey, that $1,000 mortgage payment will barely be anything in 2040, just keep paying the minimum, put your money in and index fund, and drink a beer."
Same logic applies here. Calm down, do the math, and I think you'll find that you'll come out ahead utilizing REPAYE.