He is my brothers best friend and he treats me more like a girlfriend then an Aquantance, he texts me all the time and when I do see him he tells me he loves me and he plays around with me in a flirtacious way. What do I do? And am I taking his actions over the top because I like him?

Does not matter, what level a 17 year old "dates" at, is far more advanced over how a 13 year old will date. Even if he is meaning this ( and I doubt he does) he does not matter.