Michael Clarke Duncan -- Planned To Wed Omarosa in January

Michael Clarke Duncan and Omarosa Manigault were secretly engaged and the wedding was set for this January, TMZ has learned.

Sources connected with the couple tell us, Michael and Omarosa kept the engagement a secret from the media ... only telling very close friends and family about the pending nuptials.

We're told the couple had just started planning for the wedding when Michael went into full cardiac arrest​ July 13 and was hospitalized until his death.

We're told Omarosa is just destroyed after waging a valiant fight to save Michael. She had doctors flown in from all over the world but constantly worried if she was doing enough.

Michael died while still in the hospital Monday morning. He was 54.

Omarosa, who had just left town for an engagement before Michael's death, returned to L.A. last night ... and was sobbing uncontrollably at LAX.