<human>: Can you give me a shortened version of the text?

I am a mid-20s female, dating a mid-20s male for almost 3 years. Long story short: Yesterday I was checking my email on my boyfriend's computer, didn't realize he was signed into Yahoo and stumbled across a slew of old conversations with a girl he made plans to meet up with and have sex with. I know he occasionally goes online and has sex chats with random girls, exchanges some silly pictures, whatever, but he never gives them any personal information and it's just to masturbate so I really haven't worried about it.

This meetup with the girl happened about 2 years ago, almost a year after we started dating. I was beside myself. He's a very shy person normally, and has a very hard time talking to girls in most situations. 

As far as I can tell this only ever happened once, just sex, not a girl he ever saw again or even heard from again. I don't believe he has ever cheated since and I honestly (though perhaps naively) don't believe it will happen again.

Other than this, our relationship has been very happy and smooth. We recently adopted a dog together, took a week-long trip together, and we are planning to move out of state together next year so that he can be with me when I start my new job. He tells me he loves me (although he has never been overtly affectionate or romantic...but there's a long history with his parents there, so it has never bothered me) and I have never doubted his honesty until this happened.

I'm a little bit in shell shock right now, so I'm hoping someone with a clear mind out there can help me sort through this. My question: has anyone out there forgiven something like this? If so, how did it work out? I'm not sure how to approach it, and I'm honestly leaning toward just asking him about it and probably forgiving him (assuming it hasn't happened more than this one time). Advice??

If you have any questions, I'll try to check this a few times tonight and answer with more info if needed.
<bot>: Bf cheated about 2 years ago, I believe it only happened once, other than that our relationship is great. What to do?