I like two people at the same time i don't know what to do?

One of them is my bf of a long time. I am very comfortable with him, I love him a lot, he is the closest to me. He is a very nice guy. However, sometimes he behaves in very non - understanding fashion. He is also very stubborn and never accepts his mistake. His views are a little orthodox. However, I know how to deal with that but we have a love-hate relationship because of our differences. Our fights have gotten violent on both ends. However, despite all of this horror in our relationship, I trust him the most, love him the most and am truly myself with him. He too is very comfortable with me. But now I am strongly attracted to this cassanova, who has a VERY BAD BOY image. Surprisingly, we have the same interests to the core and also share a zodiac sign. But I am aware of this other guy's design to just have sex with me and nothing more. I know that he cannot love me like my bf does and that I will never be that comfortable with him as I am with my bf. But still, I cannot resist my temptations and I even told the other guy that I am in a relationship and that was the reason behind my avoiding him earlier, but he still messaged me (the message meant nothing like he likes me or something he just wants to **** me) but still I am attracted to him. I can't help it. But I love my bf too much to cheat on him and can't think of life without him. But I am very very confused. I have no idea what is wrong. Its stopping me from focussing on everything else. Please help somebody and tell me whats going on and what can I do about it?