If she had given you a decent amount of notice about her non-attendance, I'd say she was off the hook paying for the tickets. You would have had time to make other plans - to find a legit way to sell the ticket or find a friend prepared to pay.
As it was, she bailed last minute. Being placed in a situation where you're trying to find someone while you were driving to the event is insanely last minute.
If you'd gone alone because of her snowflakey actions, she would have been up for paying the ticket cost.
If you found someone who could go with you but who couldn't afford to pay because of the short notice (which is what I'm assuming happened), then the SS is still up for the ticket cost. (Although if I was the one who went with you at the last minute, I would have offered to pay, even if I couldn't cough up the money then and there.)
If the friend who went with you did pay for the ticket, then of course the SS is off the hook for the cost of the ticket.
All of this is likely to remain hypothetical. Because from what you have described, SS would not pay for her ticket even if her absence had meant you were unable to attend.
It sounds like the wider group now have a pretty good idea of what happened. Back away from the SS and let her continue to dig herself in deeper. As jedikaiti said, "she doesn't need any more rope".