Ah I think I understand the underlying problem here. It's like saying when ice metals and becomes water, the ice no longer exists. But we know this isn't true. Rather the ice exists just in a different matter state. Matter and energy share a similar concept. The problem is the Law of Conservation of Matter and Energy isn't exactly saying matter cannot be created or destroyed. The definition we get in most text books is just a simplification of the concept.

A better way to express the Law is to say something like "The sum of what you put in will always equal the sum of what you get." It's saying that in a perfectly closed reaction nothing is ever gained or lost, eg. created or destroyed.

Does that make sense?

I like to see things in simple terms; matter distorts space-time. And I have in my head that rubber-sheet model of space, with bodies flying past each other and having their trajectories deflected by the distortion masses cause. It's neat.

Oh, I already understand the theory perfectly, that's no issue.

I think the problem was mostly one of semantics or definition. Science doesn't care much about what definition you give a word, as long as everyone has the same. Perhaps this wasn't the case here. I wasn't writing a lab report or anything like that, so I just used the words with the everyday definition closest to what I wanted to say, and in not so rigorous ways. I suppose it can cause misunderstandings. Mea culpa.

I think the main problem with your water analogy is that the water hasn't changed, at least chemically speaking. It's H20, nom matter what phase it's in. This is why I preferred the analogy of it becoming vapor. Yes, it's still H20, but it's drifting apart from itself, essentially becoming something entirely different.

And my interpretation of how the Law should be written is, "Matter cannot be created or destroyed but can be converted into energy."

But Matter and Energy are the same thing, so your law is redundant. The law you're looking for is the law of Conservation of Energy.

Does this same law apply to matter as well? Or would that need to be added? (Maybe it's implied...)

It's implied, because they're the same thing. Matter and Energy are one and the same. E=mc^2 ring a bell?