Our tenant wanted out of contract that was for two years but was to pay two months rent .How can we collect?

Tenant asked to get out of contract in February as she was offered a job in the mountains..In our contract with her , she was to stay for two years or pay two months penatly.We agreed to let her out and was just going to keep her deposit as one month and forgive the second month. She got a lawyer , lying that we asked her to move and demanded her deposit or take us to court. We sent her deposit. Now ,how can we get our two months rent ? She rented from us for three years. The first year was in contract for two years. She wanted out in a year or if we lowered payment she'd stay. We did . She stayed. Another contract for two years. She wanted out the next year. We let her go. She moved .Put house on market to sell.She called in a month and wanted to move back. We hadn't sold so we let her move back with another contract for two years. This was August, then in February she wanted to move again. So we think we've been very fair to her for her to act like we were the bad guys.Thanks