Freaked out about getting sued, what can I do?

I bought a study guide for a test to get into graduate school off of a website put up by a teacher. We had to sign a contract saying we wouldn't illegally distribute the study guide after purchase, so I signed it and paid. I received the study guide and have decided that I no longer wanted to pursue this career path, so I sold my copy on ebay and in the midst of doing so accidentally put up two additional ads for the same item not knowing they were there because it was my first time ever selling on ebay. I wasn't getting bids on my item at first so I put them up. Now the teacher informed me that he suspects me of selling multiple copies of his work and will be using my signed document as litigation and has already spoken to his attorney about this. He is in another state, but I'm young and have no cash or experience ,nor the time to deal with something like this. I just sold my copy which I saw many other individuals do online, I didn't sell multiple, who in the world would have time to copy hundreds of pages anyways?