I hate this…

Me F18 and my friend M17 my friends girlfriend F19. Okay so me and my friend we were having deep conversations these past 4 days and in those days he would tell me “if only I had asked you on a date back then” which left me speechless so I didn’t say anything because he already has a girlfriend. Then today he said he can’t stop think about me and that “if he could he would date me” and I’m conflicted I don’t know what to do and I do like him but I just got out of a relationship and I need some advice on what to say or do cause it’s bugging me on what to do.