The problem with antimatter particles is that they cannot exist in the same place that you do. The atoms that keep the air and space around you whole, and provide the surface that you're standing on would not sustain the person made up of all oppositely charged atoms. Not unless you and the antimatter person both met in a vacuum of space. That's how my professor explained it to me. Physicists would roll in their graves at reading what we just laid down and not because we did a good job lol.