Football hall of famer, talk-show host, sports commentator ... and cheater?

Michael Strahan was unfaithful to gorgeous fiancée Nicole Murphy -- and that's why she broke off their engagement, announcing their split to the world just a day before Strahan's induction into the Pro Football Hall of Fame last week, according to a new report from TMZ.com.

Murphy reportedly "confirmed" proof of Strahan's infidelity on Friday, following several weeks spent looking into his allegedly illicit activities. In early July, Murphy, 46, "first got wind" that the former Giant, 42, was seeing another woman, TMZ wrote.

Other sources told TMZ that the pair has actually been dunzo for several weeks, having been "on and off" since Strahan landed his co-hosting gig on "Live! With Kelly and Michael" two years ago.

The exes, who have nine children between them, dated for seven years. Strahan was married twice before, while Murphy's ex-hubby is actor Eddie Murphy.