How did the big bang happen when space and time came into existence at the big bang? How is that possible ☺️?

There is plenty of evidence for the big bang, both with mathematics and physics. It has been traced back to 10 to the minus 32 of a second after the event, when the whole universe was the size of a grain of sand. 

Physicists can explain it in detail, but I find it difficult to comprehend and imagine how it all came from nothing, and to understand the concept of nothing or T=0.

You are not able to understand the mathematical models.  Unless you can mange the calculus of the maniflods of space time you can only be a bystander asking for answers you'll never understand.

Don't know, science is working on it. Many possibilities exist. It does not mean big bang didn't happen, or that some god did it. 

OOOOOH, you got us. The creationists win. You found us out. How come if evolution exists elephants don't pee diamonds? Yeah, huh? Answer that Mr. Scientist. And if the earth isn't flat then how come my house doesn't have a curved floor? Huh? And if global warming exists then why was it 60 degrees today if it was 61 yesterday, huh? Creationists, we win!

The idea that space and time came into existence at the Big Bang really isn’t supported by any evidence - it is an assumption because we don’t understand the laws of physics at the Big Bang event. We do not know what could have predated the Big Bang. There could very well have been some form of space and time prior to the Big Bang.