50 Cent Sues Ex Daphne Joy for Defamation Over Rape Allegation

50 Cent's through trolling his ex, now he's brought lawyers into it, and he's suing Daphne Joy for publicly accusing him of rape and physical abuse. In docs filed Monday, and obtained by TMZ, 50 blasts Daphne for her Instagram post from March 28, where she made the allegation behind his lawsuit -- and he says she only did it because it came out that he was going to seek sole custody of their son, Sire. 50 says he…