Difficult conversation prep

I need to have a hard conversation with {{person}} about {{topic}}. The outcome I want: {{desired_outcome}}. What I'm worried about: {{concern}}.

Help me prep: 1) The one sentence that captures what I actually need to say, 2) An opening line that doesn't ambush them, 3) Three things they might say in response and how I'd handle each, 4) The line I should NOT cross even if I get emotional, 5) The minimum acceptable outcome vs. the ideal outcome.