How should I handle the situation with him?

First of all, I am a straight guy. I've got a friend at school through a female friend. I play badminton at school with her, who also plays with him. Since he got to know me, he doesn't ask her to play anymore, but asks me to play with him instead. In the games, he asked about many things including whether I had girlfriend or not. Simply and honestly, I answered that I was single. We became pretty close friends in short time since we have the same sport in common. Later on, my female friend found out that he didn't want to play with her anymore. At times, I tried to organize double badminton games by inviting her to the game. In his back, she told me that he liked me because he didn't ask her to play with him anymore, but asked me to play. Since then, I was aware that he approached me. To me, he is just my best friend. So, I gave him clues that I like girls only. Also, I have a girl (my crush) at school. Last week, he asked me to go to a bar. I wanted to study him more so that I agreed to go. In the bar, he said, he knew that I have crush on a girl at school from my friend. Then, we talked about girls at school. I felt relaxed that he was into girls. But, sometimes, he also gave me flirting gestures while we were playing badminton games. My other friends even noticed his flirting. I am totally lost if he is gay or not. If he is, how should I deal with him? I mean, I don't want to give him any false hopes, but on the other hand, I also don't want to break the friendship with him. All ideas are welcomed and thanks for your time.