How do I reason with an Unreasonable Daughter?

I want desperately to get along with my adult daughter but no matter what I do, it either ends up unfavorably or instigated by some convalutent competitive gene unbeknownst to me. I never signed up for any competition, least of all one with my child! I've seriously clung to the belief that when your daughters grow they wil become enlightened. Yeah, ok. "Time" would improve our relationship and open doors of communication between us (the mom) and her(the daughter) would swing open to a new universe of love and understanding. Nice but that theory just hasn't worked in my part of the universe. Other than my daughter having so much hate directed at me for reasons unknown (we are virtually like oil & water), we seem to be a normal family in other ways. What a dillusional thought. The reality is that some times grown "adult" children just simply don't give a crap. Conceptively, I understand but Emotionally it's still a daily struggle. As the last child and baby this daughter is whole-heartedly and sincerely admittedly spoiled rotten (I totally take full responsibility for that) but I always believed she loved me. Perhaps I thought "she owed me" but I got my payback: She's a mean girl. I don't know where the intensity of her hostility stems from, nor do I know how to divert or subdue those aggressive behaviors when it becomes scarily confrontational, but I won't keep punishing myself for thinking I misguided her or excusing her brutally insensitive nature by saying she "must have had a bad day".