<human>: Can you summarize the given text in a few sentences?

I had a girlfriend last year from July to November. For various reasons, I started to feel the relationship was getting to a serious point, and I wasn't feeling peace about heading that direction, but was uncertain if I should end it.

In the span of time that was my uncertainty, I was using her laptop and saw a new Facebook message notification, clicked the message box, but quickly realised I wasn't logged into my account. It was too late, though - I saw a guy's face and "hey baby, been missing our talks" as the message lead. Turns out he was in Afghanistan and she was carrying on something with him long-distance. Her relationship status was hidden, and I didn't use it to tag us in anything, neither did she, so there was nothing to advertise she was in a relationship.

Being the boyfriend, I messaged the dude and let him know she and I were in a relationship and I was ending it, but he deserved to know what happened. I broke up with her immediately. She then, after I dumped her, proceeded to beg me not to say anything to him and that she didn't want to lose both of us. Oops.

I kind of forgot the whole ordeal, and it took one night's sleep to really kind of get over it since I was already on the fence about ending it and didn't take the break-up or her lying too hard.

Life went on. Months went by. I never heard from him.

Until yesterday.

Turns out they got married last month. I assume he just checked his "other" box, and just now saw my message, because he sent me a rather frantic reply like this was very recent or present history. What do I say to this guy now? I'm completely moved on, completely apathetic to their marriage, and am actually feeling really bad for him. His message to me seemed upset. He asked if I was serious, how this could happen, etc.

They just got married, and now it seems to be undermined. How can I handle this?
<bot>: guy married my ex a month ago and just found out we had been in a relationship when he first got involved with her long-distance, and is upset. Unsure how to handle.