If it is the heat, I think you are done for.
But it might not be.
I would try starting again, sort of. Would add the lemon, or vinegar to the bottom of the pan, the cleaned pan you started out with. And then add the broken mixture very slowly, under very mild heat. Whisking like crazy all the time.
It can work. But there is no gaurantee to that procedure. Good luck.
Before criticizing a person, walk a mile in his shoes - then you are a mile away and you have his shoes!