The truth came out because I said to him that things didn't add up, I told him I'd be fine if he told me the truth and we could work it out. He then admitted the truth and I got a lot more upset than I intended. He then got very upset and tearful too, he promised me that our relationship is different and he'd never sleep with anyone else and never wants to.

I am going to forgive him. I have forgiven him, actually. I am still hurt though and need time to recover from it. Thank you for your reply and thank you everyone else, every reply has been helpful I appreciate it.