I'm sorry you are struggling with this loneliness. In my case it is me that has left the world. I imagine the world to be a parade. And I'm sitting on the curb watching it trail off in the distance over the horizon. But then I'm old. So it's okay. I don't recommend what I do for younger folk though.

Here are links to 5 articles, from PC's archives, on the subject of loneliness. The first article, by DocJohn, provides links to a number of additional articles on the subject:

Loneliness & Being Lonely - Psych Central

How Do You Heal Loneliness?

7 Types of Loneliness (and Why It Matters)

Does Your Attachment Style Keep You Feeling Lonely?

All By Yourself? 10 Ways To Overcome Loneliness