This may not be the same person, unless he married again late in life, but there is a will at the National Library for a Roberts Edwards of Llandderfel who had a wife, Jane.
It made on 7th February 1758 but might be 1759 if using the old calender. It was proved in 1768 and so he may have lived for ten years after making it.
He has grandsons with the surname of Thomas and Roberts and a daughter, Margaret.
Regards,
David