I don't know if I should break up

I started dating my boyfriend when I was 14, I loved him still do but sometimes I think I committed too soon. Sometimes I feel there are many things yet to be experienced. It's been 4 years now and I am 18. Lately I've started getting attracted to different guys, I feel guilty but I can't help it. I feel like I should take a break because I am not ready but that would mean I'd have to lose him. And if I do break up it would hurt him and shatter him break him completely. He's very loyal and loving but I don't know if I have changed. I can't imagine living without him but sometimes I feel like starting new. We've had extremely bad fights in the past and he has treated me like shit but now he has changed but those things are still stuck with me. I don't know what to do. I feel like I am cheating on him since I get attracted to other guys.