Should I give him a chance?

Me and this guy dated back in december and we are both the same age (15) . But we weren't together that long because I broke up with him. I broke up with him because he was really clingy and it got annoying after a while. Plus he had a reputation for being a player. He even told me that he couldn't say how many girls he dated in his lifetime because he lost count. So I felt like I could never fully trust him. Even when we were going out I heard from other people that he would flirt with other girls behind my back. I confronted him about it but he just denied it. But he never really did anything to me personally that made me not like him (besides being clingy) , it was mostly just things I heard from other people. But I didn't know who to trust more, this guy I only knew for a few months, or my good friends I practically knew my whole life. So I ended up taking my friends side and broke up with him. After we broke up I never contacted him but he always contacted me. So we only ended up talking when he started the conversation. And in almost every conversation we had. He even flirted with me he got a girlfriend in May! and that only led me to believe that he was more of a player since he flirted with me while he had a girlfriend. Last night we were talking and he told me that he still isn't completely over me and it took months for him to move on to a new relationship. He said that he misses me and wants to date again. This was the sweetest message he sent me last night:" Thank you :) plus why would I try so hard for some girl when I could have someone else. Cause I like her alot and I enjoy being with her and she could have the worst have the worst hair day, wearing the ugliest baggiest clothes, and wearing no makeup and I’ll tell the world KELSEY IS THE GIRL I’M CRUSHING ON. " :D It made me so happy and it made me remember the sweet things he used to say to me when we used to go out. He really makes me happy but at the same time I feel insecure with him because people say he's a player/ he flirts with girls when he has a girlfriend. What should I do? Should I give him a chance?