history: My girlfriend was cheating on me but I didn't know. I believed that she would never cheat on me.  My girlfriend was cheating on me and I didn't know.  Oh man that's a bummer.  Did you leave her or are you giving her another shot
current: She left me. I believed she would never cheat on me until she told me she was dating another guy
next: Dang that's harsh homie...so sorry to hear that bud.  Don't worry as much as it hurts now she did you the favor of kicking herself out of your life...you deserve better than her 