If your boyfriend isn't a Christian, then I think that you're right - you need to break things off. It won't be easy, I'm sure, but the longer you wait, the harder it will be. I will pray for your heart and your comfort.
Talk to God about how you feel, and try to "give" Him your sadness. Hugs, sis... it isn't easy but I KNOW you can do it! And you'll probably be glad you did after a little while.
P.S. Welcome to cc!