"It is in the infinite ocean of myself that the mind-creation called the world takes place."
(Ashtavakra Gita)
Our world's are illusions. We actually don't know that we exist at all.
However, assuming that humanity shares at least one illusion - that of science - then we are all composed of tiny particles, quarks or some such, precisely as is everything else. When our hearts stop pumping and we die we will subsequently, regardless of how long it may take, decompose to the level of the smallest of those particles which will then presumably, with others not necessarily from our past selves, combine to create something else - or not. Either way, those smallest of particles wills till exist, hence we will still exist - at least within that common illusion and if it happens to be a reality rather than illusion, then if fact, too. We simply won't be in the form we had.
I may well be wrong but I find it more comfortable to accept that as well as living within an individually created illusory world, l also live in one shared with all of humanity. That is comforting for me because it justifies my caring, sharing, feeling, interacting and etc.
I do believe that Eastern 'relgiions' offer a much more likley explanation of what 'is' and what we 'are' than do those that are driven by doctrines which profess to be handed down by some higher power or 'Creator' and which dictate so many ludicrous requirements of us, even contradictory ones from supposedly the same omnipotent entity.
Finding peace and/or tranquility, to me does require accepting that one illusion is as likely or unlikely as another but accepting that such is what 'reality' is for each of us, is the case.
As we can only ever prove the possible but never the impossible, then that seems fine to me.
Take care. Stay safe. Enjoy you illusion.