Don’t suggest that you’ll reconcile in the future if you know in your heart that will never happen. No matter what never suggest that you will be back soon enough and you will continue with the relationship when you know that you are done.
Because this is such an emotional conversation, your instinct may be to pull back and appear detached. But it's nice to air out your views rather than punishing your partner for what they didn't do. Be nice enough to end things respectfully rather than just being silent.
Telling them that you’d love to stay friends is misguided. It may seem like a nice gesture in the moment, but it can feel insulting. You shouldn't be friends with someone because you feel you have to console them for breaking up. Don't make them feel worse, just say yourbmind and work away.