My ex employer is suing me for a non compete agreement issue that does not exist.

I was hired in 2002 in Dallas area, 6 months later was told I needs to sign a "Non Compete Agreement". I did sign it but did to keep my emolument. In 2005 I was fired because he heard I went on a job interview. I went to work for another company in same field in Austin. He begged to hire me back and in 2006 I went back but was never ask to sign a new agreement. He was very abusive to me so when the opportunity arose I left again in 2010 back to Austin and now I am being sued for $300,000 How can this happen when I never signed a new agreement? My ex employer said that we verbally agreed to the original agreement. I never agreed to it and was never ask. Now I am into this up to $25,000 so far. Is there not anything I can do to stop this and or counter sue to regain my attorney fees? Please help???? JKE