What is the best thing to say to someone you're breaking up with?

I’m not looking for methods, I already know how I’m going to do it. I’m just unsure what to say exactly. My boyfriend is very emotional and I do love him a lot and I care about him, but things have come up and I have to end the relationship. I’m not going to go into why I’m breaking up with him (so please don’t ask) I just want to know what to say because I’ve never done this before and I’m having a lot of anxiety about it.