One more time.
Within the context of general relativity, there are NO singular points in spacetime (aka the universe). Therefore the statemetn that "the universe began as a singularity" is meaningless.
The singularity theorems of Penrose and Hawking show that it is impossible to indefinitely continue timelike geodesics into the past. That is the sense in which there is no "before" the big bang.
Quite a few people who write popularizations, including physicists who one would think should know better, do not understand this point. Perhaps they too ought read the original papers by Hawking and Penrose or the book by Hawking and Ellis, The large scale structure of space time and learn what the singularity theorems actually say.
I have no interest in continuing to rebut each and every over-simplification or popularization that you care to drag out. As I have told you there are a lot of misconceptions, over-simplifications, and downright erroneous statements that have been publlished. The nature of the singularity theorems is precisely as I have stated. The usual interpretation is that general relativityis inadequate to describe the earliest moments of the universe, not that the "universe began as a singularity". Given the apparent breakdown of our best available theories, no one has a clue what happened at t=0. No one includes the people who wrote the books that you are reading. Unfoertunately the accurate answer, "I don't know" doesn't sell books.