So, antimatter is real... but its also not scary.
Hear me out. Everything around you is made of matter - particles like protons, neutrons and electrons. Antimatter is almost exactly like all of that regular matter. It just has the opposite electrical charge. Like, electrons have negative charge. But an antimatter electron, called a positron, has a positive charge. And that's basically the only major difference.
I mean, there are also some very tiny other changes, but they're just beside the point here. 
See, not scary.
There is the part where if a matter particle hits its antimatter counterpart they'll, like annihilate each other and release a bunch of energy. But that's also not anything you need to worry about because there is an disturbing lack of antimatter in the universe.
Oh why? Well congrats, you've just discovered one of the biggest mysteries in physics.