Nothing That Matters

Big Bang is the accepted theory of cosmological origin of our universe.  How could a very small singularity in space time generate a whole universe?   Why is there only matter without much anti-matter in our universe? One explanation is that the Big-Bang singularity created two different universes - one of matter (that we are part of) and another matching one of anti-matter.   Thus a pair-production out of energy of photons/bosons would have taken place.
Discounting that such a anti-matter universe has not been detected (nor seriously sought out), from where did so much energy come for whole mass of two universe to be created.   How could such huge energy be concentrated in a small area?  Theoretically, what is the maximum energy density possible?
  Big-Bang is good theory and has excellent fit with the observations, but the big question is who bankrolled the energy of this big-bang?