Welcome back, its good to see that you are still around.
I would say its pretty natural too, the feelings you are having. Losing a relationship is like losing anything else, there is a mourning process. You mourn the loss of one part then you realized something else that you've lost and seem to have to go through the grief all over again. I think if you look closely at what you are feeling you will see that you are in fact mourning another feeling and not the same one as before.
I know its not easy and I don't want to sound like a smart-ass but it is progress.
I'm sure you will find someone who will appreciate and give you what you are missing now.
I wish you all the best,
Its times like these we learn to live again,
Its times like these we give & give again,
Its times like these we learn to love again,
Its times like these time & time again.
-The Foo Fighters