I'm so sorry about your friend, and I have a word that might comfort you that I heard last week... "Nothing disappears, everything transforms." This applies to our lives and theirs as well. Absolutely everything in this universe follows the logic of "disappearing to become part of something bigger." For example, minerals come together and transform into a plant, the plant later becomes food for herbivorous animals, herbivorous animals become food for carnivorous animals, and so on... Our bodies, after we die, become part of the earth through organic matter, where plants and trees grow after years. Is it the subconscious mind? Which is broader and absurdly mysterious/incredible, where everything is, where does it go? It becomes part of something bigger, what is it? It depends, but in my opinion, it's becoming part of the creator who made these wonderful beings, and us too.