I like the Back To The Future reference. In that scenario, it still posits that everything that has happened still happened, as the time traveler would always wind up "resetting" what he did by going back to before he did everything. It feels a bit timey-wimey at first, but when you step back to look at it, it really simplifies things. Everything still happened, it's just that he went back to prevent everything so that for other it would feel it never came to pass. But, it always happened because he remembered it happening.