Ending a serious relationship?

Obviously we will have a conversation about it, I could never do a text. But how do I start? What do I say?

We have serious plans about our future, and it might come as a surprise to him, but I have very good reasons and I would like to keep some things out of it. He has been manipulative, abusive both physically and emotionally, controlling and gas drained the life out of me. He has also been extremely nice and caring at times. Obviously, I wouldn't be a bitch and say well you did this, but rather have a heart-to-heart discusion on why it's the best for both of us. How do I gently approach him, and give good points? Please give me advice.