CM, you have options at eighteen.Always remember that you ARE the boss in your own house. Your house/your rules. You don't like these simple rules, then find somewhere else to live. At least...I never cared for feeling like 37 ruled the roost over the rest of us and it came to an end one day...
You can write out a contract in advance and let her see it:
"Mom's House Rules If You Live Here After Eighteen"
1. Chores must be done without complaining. You are not a child and can do them yourself now.
2. Either college or a full time job required.
3. If working full time, $200 rent and no allowance anymore as you are an adult. You also pay for your cell phone and any car expenses.
Blah, blah, blah...use your own standards, your own rules. If you show it to her in advance, let her have a fit. Go in your room and lock the door. Or take a drive. Or ignore her. If she gets violent call the police. These are just suggestions of things you can do if she blows up, knowing it isn't going to be "You're 18 so you can have a ball with no responsibility!" There is no excuse for somebody her age to have a toddler tantrum. And there is no reason on earth for you to let anyone abuse you, including your adult child. That's how 37 got tossed out of the house. I finally had had enough of his horrible words, his lack of listening and respect, and his threats of violence.
Hugs. You have many options. It is always good to have a plan in advance, before the dreaded event happens. You can always hope it won't. Showing her your expectations in advance may make her think and have a more realistic attitude of what life will be like living in your house as an adult...you never know. It may even make her decide to do something with her life after high school, never a bad thing