My project has always been open-source and differs from Ismatov's in that my main audience are nonprofits and schools (who then share my app with students; it's a B2B2C model) while his audience are solely paid tutors.
What should I do now that he's "stolen" my name? Should I reach out to him directly? Or should I get a trademark and ask him to rename his project? What would you do if someone took your startup name?