power of attorney issues

i need some advice, my husband is in the military and before we got married he had to give power of attorney to someone and he gave it to his mom. she lives in Tennessee and we are stationed in california. she used the power of attorney to open three credit cards in his name and she put her on them also and maxed them out. they total about $11,000. this was almost three years ago. she didnt ask him before she opened them but he found out later and felt bad for her and he has just been letting her pay on them and we never even see the bills. the other day i pulled our credit report and found that she is over the limit by almost $1,000 on two of them and she is 120 days late on them also. our credit cards are perfect, we have never been late and they are all under the limit. we would have perfect credit if it were not for that. we have two leased cars and one of them we are going to try to trade in soon. Is there something that we can get her to sign to show that she is making the payments on those three cards and that shows she is the one responcible for them? will creditors even care if we have something like this? I just dont know what to do? Is there some way to shift the debt back to her since she is the one who charged everything on them in the first place? we dont even have cards to those accounts. thanks for the help, S. Johnson