What to do when your best guy friend starts flirting with you then breaks your heart?

okay... so i have this friend... lets call him Sid... and we are reaaally close. Yesterday, he started texting me and saying he loved me and I like him too so i said so. Then today at skool he didnt say anything about it and it was a little awkward. This afternoon Sid texted me again and was flirting again.We somehow got on the topic of our friend, lets call her Lauri, and Sid said he liked her too. By this point i was kind of mad and sad so i told him that if he liked her he couldnt just string me along. Then the conversation ended awkwardly and he only said 'okay'. I dont know what to do or how to act when i see him tomorrow. I dont want to ignore him, cuz we are like best friends and i dont want to be all nice to him either because he hurt me. HELP PLEEZ!!!