If everything in our world were made of antimatter instead of normal matter, the interaction between antimatter and matter would lead to annihilation. When antimatter comes into contact with matter, both particles would undergo a process called mutual annihilation, resulting in the complete conversion of their mass into energy.
During mutual annihilation, particles and antiparticles collide, releasing a tremendous amount of energy in the form of gamma rays. This process is governed by the principles of conservation of energy and conservation of momentum. The resulting energy release would likely be destructive, as it would involve a significant release of high-energy radiation.
So, if you were to touch something made of normal matter while being composed of antimatter yourself, the mutual annihilation between the particles in contact would generate a large amount of energy, leading to destructive consequences for both sides.
Fortunately, our universe is predominantly made up of normal matter, with only trace amounts of antimatter observed so far. The reason for this asymmetry between matter and antimatter in the universe is still an open question in physics known as the baryon asymmetry problem.