Dear Liz: My wife and I both had excellent credit scores. Now mine are in the dump. I co-signed for a friend’s daughter’s school loan 10 years ago. I know now this was a bad mistake. I guaranteed $25,000. Now two things have happened: The daughter quit paying the loan and the friendship took a bad turn.

This is seriously hurting my credit. We have already been told when trying to refinance our mortgage that we’ll need to fix the school loan, which is showing more than 90 days behind. The outstanding balance is $20,000. I can pay the loan off. Making payments just adds interest to the problem. Are there any other options to repair my credit that don’t rely on the daughter’s ability to keep the loan current?

Answer: If you can pay the loan off, then do. You are legally responsible for this debt, and the longer it goes unpaid the worse the damage to your credit scores.

If this were a federal student loan, you would have the option of rehabilitation, which can erase some of the negative marks on your credit reports after you make a series of on-time payments. Because it’s a private loan — I know this because federal student loans don’t have co-signers — you probably don’t have a rehabilitation option (although it certainly doesn’t hurt to ask).

Once the loan is paid off, you can proceed with the refinancing but you probably will find that lenders want to base the loan on your battered scores, rather than your wife’s better ones. That means you might not qualify, or you might have to pay a much higher rate. If she can qualify for the refinance on her own, that’s one option. Otherwise, you might have to wait for your credit to heal before you refinance.