All kids do stuff like this, before they fully understand life and death. Partially, the culture in which we're raised teaches us to view bugs as mechanical things, not as sentient creatures capable of suffering. Don't judge yourself for these mistakes, they are common to human experience. Instead, use them as a basis for compassion for yourself and for others - kids and adults - who haven't yet learned what you have. They aren't evil, they're just ignorant of the beauty of life. By transmuting your past mistakes into present and future compassion, you even transform that caterpillar's death into a meaningful event that improves the world as a whole, by teaching you to perspective and compassion. All is love, anon.