Whose, mine?
It's simple (no it's not, time travel stuff never is). But I'll try to make it simple.
Let's say one day I threw a rock in a pond, then went back in time and this time didn't throw the rock. Now there are two ways to see the outcome.
1) There are now two different timelines/realities, one in which the rock is in the pond, and one in which it isn't. Or,
2) There is only this one timeline/reality, where the rock is not in the pond, as in this new changed reality it was never trown in there.
Does that make sense?
So the way I see
MM is the second, that there's only one reality and you keep changing it. Others think it's the first one, and that they create a different reality every time they go back in time, thus leaving the people in all the other realities to die under the Moon. I find that pretty depressing, which is probably why I prefer to think there's only one reality.