My Boyfriends in jail when I went to visit him tonight I found out his ex-girlfriend was just there visiting?

him, from the guard when she told me I felt like I was going to puke my stomach was in knots, my eyes teared up and it took everything in me to hold back crying, I was so disspointed and thats the first time hes ever dissapointed me, half me says forget him, and half of me says he didn't mean to hurt me... I'm so angry I need someone elses perspective please!