Why would you think she didn't sign her own copy of the contract? It wouldn't matter that she didn't sign yours, if she has your signature on her copy that's all she would need to take you to court if you breached it, and it doesn't appear like that's happened yet. Or do you have the only copy?
Logistically there are COVID-related issues with international travel and quarantine depending on the countries involved, and I don't believe she can add her travel costs (air fare, hotel, potentially time off from work if she has to quarantine at home after she returns, etc.) to her lawsuit.