<prompt> Human: So I found out that I owe about 1.5K when I was being interviewed for secret clearance during the middle of the semester in school. They showed me when the card was open and closed. I had no idea about this card at all. A couple weeks after the interview a debt collector called and mentioned that same amount of money that I owe. They mentioned that I could pay 13 of that price to basically make it all go away but I knew that it wasnt me so I was not agreeing to that payment. I asked them to send me the list of items purchased on the card. They asked me to confirm the address and my address did not match my address at all. So I gave them my address so they can mail me the bill of material. I couldnt see the bill until late may when school ended for me. The purchases on the card were definitely not me so I called them back and told them that this is fraud and I had no idea about this card. They mentioned that they were going to send me the affidavit to sign and mail back. But now Im in Chicago for the summer interning at a company. So I gave my parents a head up so they can mail it over here when they receive it. But when I mentioned that I was I planning on signing the affidavit, they asked me to make sure that it wasnt my sister using my credit card.. confusingly I told them that I never had one.. But they reminded me that I signed up for one under my sisters account 2 years ago during spring break. I remember I was stressing over a test and studying for an exam and I mustve just brushed over the fact that I was signing to get a credit card with my sister. And now thats coming back to bite me in the butt. I confronted my sister about using the card and she denied it over the phone. But now that I look at the stuff purchased, it makes sense that it was her. Im so upset about it, how can a sibling be so selfish to destroy someones credit like that? At this point I dont know what to do. Fill out the affidavit? If I do, does she get screwed over? jail time? I come from a family thats pretty crazy in my opinion. They wont speak to each other for years over something small. And Im afraid this will ruin a lot.I was actually planning on signing up for a credit card soon since Im pretty upset at myself for being late in the game. Im currently 23 years old and plan on being in school for 1 more year to get my Masters Degree. I tend to have tunnel vision when Im in school and only worry about school and Im making it a goal to not let that happen during my last year. Im not sure if I shouldnt apply for a credit card until this credit problem is solved since my credit has been ruined for the last 2 years without knowing. Should I just pay for it and move on? Should sign the affidavit? I feel like you guys will have the best approach to problem that Im currently in. Let me know if you guys need any more information.EDIT: Called both credit cards and they told me that I was Account holder and my sister was the Authorized user. I closed both accounts and sent her a text about it. She hasnt replied at and has been ignoring my calls. Sadly I have no choice but to start paying it off.  <response>: If you signed youre on the hook. Pay it off and sue your sister. 