Confused and lost

Im so confused. Im with my boyfriend of five months. But I might be in love with another. My boyfriend is the sweetest, most understanding guy i have ever met. But Im not so sure i want to be with him anymore. The other guy I might be in love with: He's not the sweetest in the world. He doesn't understand a whole lot. But, I have been in a relationship with him before. But it didn't work out. And I got over him fast. Five months later, He decides to come back to me. But one big problem, i m already in a five month relationship. But I now realize, Im not totally sure if i still want to be with my boyfriend. And I do have feelings for the other guy. But I dont know weather to break it off with my sweet boyfriend because i may not find another quite like him. But I also want to be with this other guy. What to do, What to do. Help.