Breach of a hockey contract

Hello.

I entered into a semi professionally hockey contract in September. The terms were for me to play there the entire year or be penalized (25000) if I left. (Extremely rare in hockey as players change leagues all the time). I wasn't enjoying the league and had a chance over Christmas to join a team in Europe and I took the opportunity. I gave them notice and they found another player no problem. Now they are going to take legal action for the 25,000$. Is there any way around this? Is there any arguments or defended I can do. I just wanted to play in a better league it seems unfair they limit you to do so. They're just greedy and want to get paid.