I would violate the agreement if I quit the company. If I was fired...?

Hi,

I had a bonding agreement with my ex-company. One of the conditions was that after completing one year period in a foreign country I had to get back home and work for the company for one year (transfer knowledge). One of the the contract conditions was that I would have to pay certain amount of money if I quit before completing the contract. Before I got back they fired me and now want to sue me and get money from me. Do I still have to pay or can they sue me even if I didn't quit?

Thanks.