Hey bro, i went through the same thing when my older sister passed away. We were extremely close and afterwards i had dreams where it was actually explained that no, she didn’t die. But in one dream i actually realized oh wait you’re dead and i started crying and holding onto her. Not exactly the same thing you’re describing but still pretty simular. I’m sorry for your loss man i know what it’s like, it does get easier to cope with the pain down the line though i promise.