Help with CC debt please

Hi, to make a long story short, my ex gf took cards out in my name without my knowledge, but when I eventually found out I didn’t think much of it because she was paying them off for a few months.

Fast forward, I found out I have an outstanding balance from what she used in my name, and my credit is plummeting. I’m wondering if I have any recourse besides just paying it.

I know I shouldn’t have let her do that etc, I was much more financially irresponsible at the time, and trusted her. I know better now.

What can I do?

Thanks in advance for the help