Janet Jackson 's smack in the middle of a heated battle with her brother Jermaine Jackson , and other family members, over the biopic, "Michael," and the feud all comes down to envy ... TMZ has learned. One source closely tied to the family tells us, Michael Jackson 's siblings first got into it during a phone call on the heels of the whole family getting together in L.A. last week to screen the movie, which hits theaters next month. We're told Janet was very critical of the film, while