The time reversing itself is a consequence of the interaction of particles in our universe...
If you understood the physical laws of these interactions I could go about proving that if there is a certain amount of energy in the universe, the universe will eventually collapse back on itself in a big crunch where spacetime contracts back in on itself.
But our most recent measurements show there isn't enough energy, and instead of contracting, the universe is going to expand forever.
It's not like peope just make this up, these results follow from the laws of physics and our observations of the behaviour of galaxies.
Now, concerning the matter question, why does it have to have been created? Why does something have to be created? Just because something exists does not imply creation; there is no logical reason why matter must have been originally created.
Science wants to explain the world so that it can make predictions. Scientifically, there is no evidence that matter was created. All the evidence suggests that matter has always existed and always will and that this doesn't change. Your idea that matter has to be created by someone is purely religious - in the words of a famous physicist, "there is no need for that hypothesis".