You are certainly not alone.
I feel all the same ways you do. I go through all of the emotions....sometimes all in the same day.
I wonder when I'll get to the point where I realize or resign to myself to the fact that he will likely not change. I want my son to change, I want him to do better and be better- I do. But at some point, much like we resign ourselves when a loved one is dying- and we resolve that in our hearts and minds and learn how to manage it- I need to stop thinking 'tomorrow, he'll see the light!' because honestly, he probably won't.
I used to say he was my child because I was strong enough to handle him. I don't know, now, that it's true. I thought his childhood was hard. Adulthood is much worse.