how does energy exist if it cannot be created.
Well, maybe it doesn't exist? Maybe we only think it exists?
That is scientists studying what is came up with a concept of energy and matter. This model of physical reality, along with things like the periodic table allowed them to predict the behaviour for an example germane to E=MC^2 of uranium and they made an atom bomb. The math was good.
How does anything exist? We don't know. We only suspect that it does and find it most functional to agree that it does, and that thus far we have some mathamatical models that work most of the time. It does appear that nothing in the universe exists independent of anything else, but rather the universe exists and is in constant transformation at different rates as a vast interdependent whole.
lfen