"Live!" co-host Michael Strahan has allegedly split from his fiancee of three years, "VH1 Exes" star Nicole Murphy.  Deets inside on the cheating allegations and break up inside...

It's over for former NFLer Michael Strahan and Eddie Murphy's ex-wife, Nicole Murphy, according to our source.  We're told that the two broke up over the weekend when Michael traveled back home L.A., where Nicole still lives, as Michael lives in New York during the week in order to tape "Live! With Kelly & Michael."

Our source tells us Michael discovered inappropriate text messages in Nicole's phone between her and someone named "London Taylor," and Michael was anything but pleased.

A screaming match allegedly went down with accusations of cheating being thrown around.  Another source close to the couple tells us that Nicole believes Michael could have jumped to these conclusions simply because he possibly could be doing the same thing in New York when Nicole is not there.

If you recall, Nicole was the lead video girl (screenshot above) in a very steamy video recently with a new artist of the same name.  And many were wondering why she would do such a sexualized video, and with a new artist.  Nicole reportedly claimed that it was a way for her to publicize her jewelry line, FLP.

We're told Michael left L.A. on Sunday to return to NYC for work on Monday.  He then, according to our source, informed Nicole that he needed a break, and the two have not spoken since. 

But when asked if the break up would stick, the source tells us, "Their families are so blended that it would be difficult to truly separate."

One source tells us that Nicole is heartbroken, but they're also hoping that when word gets out about their break up--it will force the two to communicate again.

Time will tell...