A family member betrayed me and left me broke

I am an 18-year-old working mom, full-time in college. Recently, a family member asked me to put my card on file for a rental car that was supposed to be paid for by their insurance after a car accident. They ended up betraying my trust and wrecking the car and keeping it longer than the insurance would pay for it, so Christmas Day (a pay day) my card was charged $2,160.51! When I asked about it they said they’re not helping me. I filed a claim with my bank and they said the merchant denied the request and they won’t let me dispute it again. The charge not only ate an entire paycheck but my credit card payment was declined as well which dropped my credit score. 

Im not one to ask for help EVER, but right now I don’t know what else to do so, anything helps!