Brown Eyed Girl
There is more than one way to lose someone. For instance, gradually over time their behavior changes until they ultimately leave you, the person who would lay their own life down for them. I think this type of loss is the most painful. It is not like sudden death or a natural expected loss. What is worse, they are still alive making it their priority to avoid you (sucker punch #2).
This happened to me and I have never "come back." You never do. You cannot control the pain at Christmas or birthdays. Periodically you still cry like you did when it became a reality. The rejection sits inside you coddling with self doubt, taking up "happy space" in your heart. You become grateful for the days you are happy, pushing back the loss into short term "forget" until that song plays on the radio.
You live in fear of hearing that they have passed which would end all hope of holding them again. There is no way you can stop loving them. Nope, no coming back from this, there is nothing one can do but pray.