This is the typical determinism induced nihilism we all experience from time to time. Let us not forget that the standard model and science are only particular ways of describing the world; not the world itself. All of our emotions and existential struggles for meaning are as real as elementary particles, and this doesn’t make them any less significant. We also know all the rules to baseball, but that doesn’t keep people from having fun playing it.

If life is pointless, and you are aware that you have no free will, then what better way to show that this is false than to willfully do anything for absolutely no reason at all. If you can do this, you can prove to yourself that the concept of free-will, too, is just another way of seeing some aspect of the world.

We can analyze the past and reason about how it came to be up to the present, but only what happens in the present moment determines what might happen in the future. And there are many possible paths it could take. See that we humans are a part of reality just like atoms and therefore have capacity to affect it. Free-will is not a scientific principle, it is a philosophical attitude. Rise beyond this fallacy.