I know what that feels like...
sometimes I feel like I just want to ... slowly fade away into nothingness...
distance from people doesn't help. Try your best to get out of the cave. Try your best to reach out to people even if they are far away right now... pull them in to you, don't wait for them to come to your cave.
I at least... reinforce the boundaries of my cave far too often... try to let people in

good luck
I know it's hard *hugs*
and keep us posted on how you're doing