help! how to breakup?

I'm planning to break up with my boyfriend whom I've been dating for over a year and a half. He didn't do anything wrong, he is literally the sweetest person I have ever met and treats me so well. But I want to try and figure out who I am and learn to love myself before I try continuing to love another person. He is my best friend in the entire world and I don't want to hurt him, but I know this will deeply. I've brung up the topic before about breaking up, but he just tells me he can change for me and begs me to stay, and I feel like if I leave it'll almost kill him. I'm so close with his family and they have done so much for me. I feel so selfish over this whole thing. But I want to start putting my feelings first. I'm a freshman in college and I don't feel like I should even have a serious relationship at this point in my life where I'm still trying to figure so much out. So.... how do I do this? This is my first serious relationship ever so I've never had to do anything like this. Someone please help. How do I approach it without letting him talk me out of it again? (Also, his birthday is this Monday, the 21st. I hate having to act like everything's fine for much longer. Should I wait until after to bring it up? It's taking everything in me not to talk to him about it today.)