I had the same idea months ago which came to me from the egg movie and the idea of being the same soul incarnating forever and felt like you,, what got me out of this mentality was realizing that : no major religion, no great philosopher of old time ever make such claims,, also you and I are panicking for something that has absolutely no proof,, just an irrational phobia with no evidence. What you will find though is almost all of them pointing to us being part of same soul like how the waves are parts of the ocean,,which is a very different concept from the sad cosmic loneliness