Denial is a coping mechanism. It fails to work as we grow more mature and can't reason out the evidences. Also, for those who were told, such as in child abuse, by the abuser that it was their fault, not the abuser's, then that also props up the idea that it really wasn't ---whatever you're telling yourself--- and you "deserved it anyway"...

Don't beat yourself up over the coping mechanisms you use to survive... working with at therapist will allow you to safely dismantled them in the future. (((safe hugs)))