A lot of great advice already.
You should be able to pay off the debt very quickly. However, in the other thread it was mentioned you've felt you're "only two years away" for several years now.
Once you have a solid idea of how you want to pay off debt, make a budget that will make it happen, and stick to it. The sticking to it part is the important part. If you are paying debt but not keeping a budget, it's easy to just keep adding to that debt. Until you have balances paid off and can use a credit card for the rewards (that won't get cancelled out by interest), don't use the credit card to pay bills. If your wife sees the "hit" when seeing a low checking account balance, but doesn't see the "hit" by seeing a high credit card balance, this could help shift the spending mindset.
Include everything in the budget as a line item. Include things that are not paid monthly, but still have to be paid (I only pay car insurance every 6 months, but I put money toward it monthly). Include house and car maintenance ("slush funds") so that you don't have to raid the emergency fund when those things come up. Make Christmas and gifts a line item, and save a little each month for those things, then stick to what is saved when the time comes for shopping. I'd also make in-law repayment a line item. Again, keeping up the "good faith" payments.
Record every single financial transaction, even if it's $1, to see where that money is going. Once you see everything laid out in how much you're spending, see where you can cut back. Allow yourselves each a small allowance where you don't have to answer for any of that spending (I give myself $50-$200/month allowance, depending on how much overtime I work).
Set your debt payoff goals as line items first. Then make the rest of your budget fit around that.
To help avoid spending-- don't bring home catalogs that come in the mail. Don't "browse" shopping sites while online. Don't watch commercials.
I'm not sure how old your children are, but, in my experience, my child did not get more expensive as he got older. Even his first year of college, at a community college, does not even come close to what I had to pay in child care when he was little. Yes, there are expenses, like sports, theater, lab fees, AP class fees, etc, that come up during school years, but just getting him out of daycare was a huge financial relief. So, if you don't have more kids, you get to look forward to that in a few years!
Finally, the tsp loan... I would only do that as a last case thing. The downfall to it is that you lose that compound interest on your retirement money as long as it takes you to repay that loan. And, if you lower your contributions to help cover the loan, you lose out on that as well. I'm not completely against taking out a loan on it, I did so back in 2008 to make a down payment on my property. However, stocks weren't making a whole lot at that time, and I repaid the loan back quickly. You do need to look at that as a cost to the loan though, not just the repayment interest. And, until spending is under control, I wouldn't take out a loan to cover spending debt.