Is the mass and energy of the universe constant?

I hesitate to ask this, since there is so much information out there, but it is a bit confusing, and a lot to go through. It is maybe not the easiest questions to answer.

As I have understood it, particles are continually brought into existence, and there seems to be the aspect of particle degradation where particles leaves existence. There is the Hawking Radiation that is supposed to radiate from black holes with positive particles and their negative counterpart particles goes into the gravity well and decrease the mass of these “holes”.

The universe seems to be accelerating too, which leads me to wonder if the universe increases in energy. Or is this explained by Dark Energy?