How do you tell a guy that you want to date him when you are going to break up with your recent boyfriend?!鈾モ櫏鈾?

This guy I like has been asking me if I wanted to go out with him.

I said sure but I have to break up with my boyfriend first.

Now I nervous to tell my boyfriend what should I do?!ゥHow do you tell a guy that you want to date him when you are going to break up with your recent boyfriend?!ゥ?
Dont lead your poor bf on. Break up with him now. He needs to be happy too!