Hi codes316,
I'm sorry to hear that. I can see how it would feel like there's something missing after suffering a loss. There are a lot of emotions that we commonly feel after the loss of a relationship, anger, resentment, sadness... .
I saw past all the times she hooked up with guys, all the angry outbursts and yelling she did at me, and all the depression/anxiety that prevented us from doing things and going out.
I hear self blame in your frustration. A relationship takes two, don't blame yourself for her share of the relationship.
It almost feels like she's the lucky one where she can just pick up her stuff and just move on. Maybe I'm just the crazy one that can't get over a person that is not right for me.
You're experiencing grief, grief is a healthy process, it's not healthy to avoid grief and yes, the pain does go away.
PERSPECTIVES: The Five Stages of Grieving a Relationship Loss