I want my parents to get a divorce
Why do you want your parents to get a divorce?
I think they'll be happier if the're single.
At the end of the day your parents have to take the decision but if they're not happy with each other, they should part their ways. There is no point in staying in a toxic relationship.
I don't like how they fight.
While you're caring about your parents and don't like how much they fight, this isn't your place. Your parents are both adults, and older than you, they will know when it is time to get a divorce if they do want one. You can talk with them instead about how it hurts you to see them always fighting, but I wouldn't push it further than that.