does gravity really exist?

Wow. I can tell you the simplified answer to this very excellent question.
Think of gravity as a sort of non-existent warping of space which interacts with one or more existing bodies of mass. What is weird, is that this warping results from the formation of mass while at the same time, causing the formation of mass!
So gravity actually does not exist as a separate entity or force! It is only empty space which has become warped by matter, and therefore acts on matter in the way we observe it to.

The gravity of that question is very grave.

But let's start with an even more grave one.

Do you actually exist. Or are you, as some propose, merely a 3D holographic projection off the rim of the universe?

Yes

No. The world sucks.