Is it actually possible to save someone?

Over 4 years ago, I dated a guy that was very emotionally unstable.  I began the relationship in an attempt to help him become a stronger person, but in turn drained myself of my own strength.
I recently found something I wrote shortly after I ended things with him.  It reminds me of the disappoint I felt in myself and the pain I caused for him.  Here is what I wrote:
~~~~~~
Is it actually possible to save someone?
Does it always result in them hating you?
Does it always end in you giving up because it just doesn't seem possible?
Won't they always be dependent on you if you do save them or help them in the least bit?


He will always hate me.
He doesn't realize all that I tried to do for him.
He only remembers that I left.
He drained me of my happiness and it seems to all be for nothing.
I hope he is at least somewhat happier and realizes how much those around him care about him and his well being.
~~~~~~


After 4 years, he still will not speak to me and thinks that I used him.  Used him for what I am not sure.  When I left him, I was drained, weak and no longer emotionally stable.  I had to build myself back up.  If that is how I left him, I am not sure what I took from him, but I do know what he took from me.