Not breathing... breathing... struggling... a spit and a sputter... a gasp... a cough... a rasp... a strange whining noise... oh, now breathing again... oh no, now not breathing again...
Depending on illness, cause, circumstances, from my experience and from what a doctor told me that can be absolutely normal for a moribund... of course, certainly not for someone who is dead already or who dies in their sleep! My father died at home like the above from from a brain tumour and spent his last 5 days, 3 on morphine in that "breathing not breathing" state so I really can't see the problem here. Agreed OP may well be lying on many things, but what is the point of him lying about this?!
And according to all reports Saayman only said Reeva would probably have only taken a few breaths after the head shot, and "probably" is absolutely not definitely not least because medicine is not an exact science. Nor did Saayman give a time span for in between those "few" breaths and my father could go several minutes at a time without a breath during which we would all think he had died until a deep breath and there he was back again breathing at times for an hour or more as rhythmically as a baby while other times rasping and gasping for a while leaving us to watch, and listen, waiting for him to die. And then he did. He died at the same time as he raised one arm in the air as if in a nazi salute and let out the most enormous sigh as if all the air in his tissues was leaving him in one go.
No, I don't believe OP is lying here, but even if I didm Nel informed the court the State accepts his story after the downing of the door so it would mean a hiding to nowhere while there are other more important conundrums unresolved.