need help about dating

so basically my mom has been hosting a foreign exchange student that is 15 and im am also 15 shes has shown interest in me and ive showed interest in her and we have been dating for a week we have went on 2 dates and we really like eachother, so her parents are okay with it but i dont know how to tell my mom, we have been hanging out so much lately that my mom has been relieved that she atleast has a friend but i dont know how to tell her, anybody have advice