You could look up the LDS film of her Andreas marriage to William Cowle to see whether she is recorded as spinster or divorced. Film no.0106705. But I agree with Brian that it is probably a story which someone made up to hide the illegitimacy.
The Andreas book (McCambridge, 2005) says Dan b.1825 was brought up by his great aunt Esther Teare Moore at the Dhowin, and that he emigrated to America in 1853. "Some of his correspondence has survived". The book doesn't have a death date for his father Dan - only b.1803, married Margaret Callister of Jurby in 1828, and that he farmed Sayle's Larivane.
The surviving correspondence would be worth locating, to see his actual words, rather than what someone else is passing on.

Sue