I am assuming this is were someone invited you to a party and you wanted to bring your best friend along, but they're not allowed.
Explanation:
This is an open response so there's no right or wrong answer. Here's what I remember writing though.
"I'll still go to the party. If they're really my true best friend, then they must understand that I'd still like to go to the party no matter if they're coming with me or not. If my best friend gets upset that I went to the party well that's on them. I'm my own person they don't enforce my decisions if they're not bad." That's all I can remember, hopefully this helps.
In English grammar, this kind of imaginary sentence is called a conditional sentence. We use conditionals to talk about imaginary situations in the past, present and future. We use conditionals for situations that might happen in the future, or situations that might never happen.