Relocation repayment/hostile work environment

I was promoted and transferred with a company on Feb. 28th, 2018. I signed an agreement to repay relocation expenses if I left or was terminated for cause within 1 year. After 3 months I was accused of something I did not do. After investigation by HR it was found that I had not done anything wrong. Within two more months I was accused again and another investigation happened. Then two more months went by and yet another investigation. This happened four more times. Then I was accused of sexually harassing a female employee. I had never even spoke to this employee before. She did not work in my department nor had I ever had a reason to interact with this employee. I was suspended and yet another investigation. I was brought back but not paid for the two weeks I was suspended during the investigation. After I was brought back I was put on probation for other offenses, but nothing to do with sexual harassment due to lack of any evidence I had committed this offense. The offenses included using profanity, disrespect of hourly employees, etc... I asked many of the employees that worked for me what happened while o was gone and a number of them said that a certain long time manager didn’t like me and was trying to get me fired. While I was out I started looking for other employment. After I returned I was investigated and found no offenses had actually happened two more times. I finally could not put up with it any more. I quit on Jan 21, 2019. Now the company wants me to repay the relocation expenses. I understand that I signed a contract, but do I have a case of fighting back due to harassment and hostile work environment?