I think at 20 they still have a lot of growing to do, I have a 19 year old son who drives a car and works full time and yet he will think nothing of pinching his younger brothers BMX bike or going out on his blades/skates ! He will be so mature one minute looking after the children while I pop out and the next he is breaking a light in the front room from acting silly !

Maybe cutting her out is a bit harsh maybe letting her know you will not tolerate her behaviour any more and that WHEN she has grown up a bit the door will be open for her to come back in with no judgments from you but untill then NO MORE !

I know that sounds harsh but tough love is hard to do and at 20 you know she can cope with the world enough to not go down and that if she really needs you as you have left the door open for her she can contact you !

Good luck !

By the way my sister was a pain in the back side untill she was 24 then she suddenly turned round and has become a great mum and house keeper even though she is severly partialy sighted ! She gets on great with my mum now and with most of the family and the ones she dont get on with are not nice anyway lol.

So there is light at the end of the tunnel....