And if we get two photons above a certain energy and slam them together we get an electron and a positron. So where did they come from and where did the photon

And if we get two photons above a certain energy and slam them together we get an electron and a positron. So where did they come from and where did the photons go? The electron emits a photon: photons from photons. And all those virtual photons that make the electron hang around near the the nucleus. It seems like its photons all the way down...