Kyle Richards did not take rumors of Mauricio Umansky cheating on her lightly. During the third part of The Real Housewives of Beverly Hills Season 13 reunion, Andy Cohen asked the OG, 55, if the speculation in the fourth installment of the hit reality series about the real estate broker allegedly stepping out on their marriage “chipped away” at their relationship over time. “He would say to me, ‘You know, we can’t care. We know the truth and you know,'” Richards recalled Umansky telling her while overcome with emotion. “Of course, there’s always that little voice in my head like, ‘What if thi…