As you seem to take forever I'll extrapolate whatever nonsense you've provided.
"I am agnostic before you ask. There is no way to prove what happens after we die, but our energy has to go somewhere.. The law applies to us, so it doesn't just get destroyed."
Firstly even though you claim to be agnostic, you seem to lean towards wanting there to be a god; understandable since that would provide comfort. Unfortunately it's the same naive thinking that conjured up all the religions we have today.
Secondly the universe is much larger than you or I could ever conceptualise, in fact we can't see beyond the observable universe, in addition it's most likely that the universe is in fact infinite. Regardless of the case this means the energy left behind (mostly heat and sound) can just spread out and get lost (it doesn't mean it's destroyed).
However I suppose on the upside, it is theoretically possible to reassemble you from this energy( though this would require technology we won't have for some time, if ever). All in all if you're worried about dying forever, you should spend more time educating yourself on singularity, nanotechnology, robotics and few related areas. As it it's obvious that you're afraid of death.