Apparently, Morris and Jay were close friends, from New York, both Episcopalians, fairly close in age, and both grads of Columbia. Morris, no doubt respected Jay--who didn't? On October 28, 1816, Jay wrote Morris was going to heaven. It could be Morris repented from his ways of fornication, got married to a woman Jay knew (his letters refer to her), communed together, and became a Christian.
Morris wanted Jay to be the Godfather of his newborn son. Jay referred to Morris as his "affectionate friend," that he had a "good disposition." This is completely at odds with his earlier reputation. I take John Jay at his word.