Candidates opposed to critical race theory swept Saturday's race in Southlake
School district had been embroiled in bitter controversy for nine months
Last summer, plans for diversity training were announced after offensive video
Conservative parents fiercely opposed plan, saying it called for 'diversity police'
Others insisted new curriculum was needed to battle racism and inequity
Now, candidates opposing the diversity plan win board seats by wide margins
It comes amid a national debate over critical race theory in classrooms