It is unknown what existed at the point in time that we define as t=0.
Actually the conditions prior to the Big Bang could have existed for any amount of time before inflation started.
In addition to not knowing what happened at this point in time, there would NOT be any way to sense anything from within any said singularity. We cannot just say that we can and ask what happens. It is likely that if the singularity was real, there is absolutely no way for you or I to even imagine it, let alone attempt to describe it.
You would never see the universe as infinite, as there is a maximum speed limit in the universe, c. You can only see as far as the conditions allow. In our case today, we can see as far as 50ish billion light years in radius thanks to expansion. Anything beyond this is not observable due to the finite speed of light.