> More oddly still as you approach the size of the observable universe, the required mass density crosses the cosmic mass density, meaning light emitted from Earth cannot gravitationally escape the universe created by the Big Bang

This is true...

> meaning we exist inside of a black hole as big as the observable universe.

This is an unwarranted jump. I'd recommend looking at the reference [0] from Sean Carroll.

[0] http://www.preposterousuniverse.com/blog/2010/04/28/the-univ...