It’s Comió. Comí also me ate but this considers yourself. For example: yo me comí un hamburguesa. Comiste refers to the person your telling or asking if they ate the food. For example: Te comiste mi hamburguesa? Or “Que comiste. You can use it like this “Tu te comiste mi hamburguesa” (not a question) I’m not the best teacher but you can trust me since I’m Hispanic. You’re learning the Spain Spanish and it’s different from my Mexican Spanish. I hope I helped
