Your daughter is 18 and I presume that is the age of consent and if so your daughter has made her bed and now has to lie in it .
In other words she has to take responsibility for her own actions and take the consequences either good or bad it has been her choice.
What you need to do is back off and allow her to make her own choices in life yet be prepared to pick up the pieces for as long as you can .
If she is determined to live in a way that is destructive or destroying her life in spite of all you have tried to do for her ,then you have to know when enough is enough and cut the ties.
People cannot live other peoples lives for them they must take responsibility for their own lives.