I don't get the whole "If she doesn't like a 10:00 curfew, she can move out" argument. Talk about going from one extreme to the other. That argument sounds to me like the curfew issue is more about control than concern.
Could be a little of both.
I can usually smell real control issues from a million miles away,
and I am not so sure that is the biggest factor here, at all....
Does the OP, perhaps, need to learn to 'let go' now that her oldest has turned 18... Very probably so....
And, as has been discussed on other recent threads... it is very, VERY, hard to let-go, when 'your baby' is still living with you as a child.
I also fully believe, that in the best interest and sanity of the OP, and her husand, younger child(ren) etc... It would mean a LOT to be able to turn out the lights and go to bed and sleep and rest, at a reasonable hour for THEIR schedule.
While I do think that the OP is being unreasonable with such an early curfew. This kid is still just 18... Still living completely at home, like a teenager, on the parent's dime... And it IS the parent's home.
I believe there has to be a happy medium.... a later curfew, a very strict lights-out, no noise, no guests policy... etc...
To those who would say that, she's an adult, she should be able to go and do as she pleases, no real restrictions...
I can say that, "no way is my 18-19-20 year old child setting up their own Bachelor/Bachelorette pad in MY home".
I fully believe that when a kid 18-19 years of age gets to darned comfortable, living at home, but acting like they have the perks of autonomy and independence... That will, in many if not most cases, breed a child who finds it acceptable to take the easy route, instead of foster independence... and this leads to a very negative co-dependent situation.... Child relies to much on parents... Parents rely too much on child, and the ability to control child in order to control their concerns, fears, etc... And, at the same time, both hate each other for it.
This kid is still just 18, but, yes, at some point, it should be RULES OF THE FAMILY HOME, or out the door.
At some point, compromise is just not realistic.
OP, I WOULD JUST SAY THAT IF YOU ARE READY TO TAKE THAT STAND RIGHT NOW, YOU MIGHT WANT TO MAKE SURE YOU ARE PREPARED IF SHE CHOOSES THE DOOR....