I have had dreams about my bf cheating on me and then found out he did I was told that if you have a dream about you cheating or your partner cheating one of you is bound to cheat Is that true?

No, it is not true. Dreams do not determine nor predict human behavior. Long before the dream occurred, you probably had some suspicions about your bf's behavior. It may be that you had been in denial for some time, ignoring signs of his unfaithfulness. The dream merely brought the obvious signals to your attention.