Re: anti-particles "moving backwards in time" ?
"...then presumably it is created at the end of its life...So this would mean the anti-verse starts out running backwards from a Big Crunch.
There is one "explosion". Antimatter particles zoom off backwards in time, building ever more complicated structures (antimatter atoms, antimatter stars and antimatter galaxies) while normal particles do the same in the forward direction; i.e. the antimatter universe is created at the beginning of it's anti-life. (More formally, "both" "universes" are created in a low entropy state and entropy proceeds to increase in their respective time direction.)
Typically a Big Crunch is seen as being akin to being sucked into a giant black hole: it's a merger of complicated systems (i.e. it's a high entropy event). So, yes, we would see antiparticles converging at our big bang from some point in our distant past. But it wouldn't look like a Big Crunch as we'd experience it. And to argue that's what's happening would be to argue that negative numbers start at minus infinity and proceed to increase until they reach zero: it's technically correct but not practically useful; better to say negative numbers start at zero and decrease towards (minus) infinity. In particular, intelligent life composed of antimatter and living in the antiuniverse would see cause and effect rippling outwards form the same big bang that created us, just like we do.
Time reversing Big Bang-Big Crunch scenarios do exist. I think yours has the added disadvantage that all matter has to be converted into antimatter. At any rate, the idea of there only being one electron travelling backwards and forwards was proposed by Wheeler to Feynman, and inspired him in the design of Feynman diagrams, which is where we started.