The thing that helped me cope and move on with my life was realizing that nobody lives in the past like this with me. They forget and move on, but I'm the only one keeping that little bubble of reality alive inside of me. It's like being the last player in a video game dungeon -- when you exit the game, the dungeon despawns.
It turns out our day-to-day realities with other people are extremely mutable. The vast majority of humanity does not cling to an excruciatingly objective past reality, it's much fuzzier for them. In a way, you can sort of just pretend you belong and join them in that weird fuzzy changeable world they live in. The rules are made up, and the points don't matter, to quote from the popular American/British gameshow "Whose Line is it Anyway?".