Which would be worse?

I have been in a long distance online relationship for a year and a half, this past christmas, my boyfriend came and spent the weekend at my house to meet me and my family. Throughout our whole relationship, I've been kind of mean to him, (I'm not really nice to anyone, its not just him) but I thought once we started spending time together it would be different. I didn't break up with him because I thought I could change face to face. At first, I thought I was right. He came over and everything was awesome, and I was nice, but now that he's back home I noticed I'm starting to get nasty again and I can't help it. He wants to move to NY to be with me, but I don't want him to uproot his life if its going to be like that, I mean everything to him, he even says he wants to marry me, and I love him, too, should I break up with him now to spare him the pain of me being like this, or would leaving him after all this time be worse for both of us? I just want him to be happy...