Does time actually exist? Did mankind just make it up

I've been wondering if time actually exists for a long time now. If the big bang theory is correct, then there was nothing before the big bang. Meaning time didn't exist either, correct? So how would there be time for the two bundle of anti-matter and matter to clash into each other anyways? Anyways, tell me what you think. Do you think time exists, yes or no?

I know a lot of people have answered, but I suggest watching a documentary by Brian Cox. He made a series of documentaries called Wonders of the Universe, and I suggest the first one called "Destiny". It has very complex ideas about time but he explains very well, and its interesting! (I'm not trying to advertise this documentary in any way)
He explains what time is, and also what could have existed before the big bang as well as many other theories.

The laws of physics break down without time. Yes, time exists. How mankind measures time is defined by mankind. Whether mankind exists to measure time or not doesn't matter. The laws of physics don't care whether you or I or mankind exist or not.

Edit: Time IS NOT a force. Force -=mass times acceleration. Acceleration is the rate of change of velocity. Velocity and speed are the rate of change of location. The metric units of acceleration is meters per second squared. Yes, I know. How can you "square" time? Never mind. Mathematically it makes sense, even when it doesn't make sense intuitively. Quantum mechanics doesn't make sense for most people. Physics and engineering are applied, real world, mathematics.

"I've been wondering if time actually exists for a long time now" you been wondering for a long time if time exist...interesting contradiction there.

But the Big Bang Theory just state that the Universe is evolving, and expanding. Nothing else, it has nothing to do with what there was before the Big Bang, so whether time existed before or not is not covered by the Big Bang theory.