Unfortunately, the post has been deleted - more on that later.

TL;DR of OP:

30 year old woman recognizes that 40 year old boyfriend is obviously upset with her and can't figure out why. After some prying she eventually gets him to come out with it: while he was doing some sort of maintenance on her computer, he came across videos of her and her ex from half a dozen years ago, doing the deed. She is mortified, as she firmly believed she had deleted all such content many moons ago. Worse, current boyfriend promptly ends the relationship, and she is stricken with grief. Kicker: he is the father of her child to be born in several months. Is he overreacting, or is this to be expected? What should she do? She is committed to him fully and heartbroken.

The first wave of comments were a mixed bag. Some feel that his response is over the top to the point that she shouldn't even want him back. Others take it upon themselves to pen weirdly long essays explaining his reaction. And finally some think his reaction was over the top, but are pretty sure he'll prove reasonable and come around before too long. Standard fare.

Fast forward a few hours and the post has been deleted, and there's a new commenter in town. The husband has arrived and fires his opening salvo: a very awkward diatribe (NSFW) in which his legacy as a severely insecure individual is cemented, including detailed descriptions of sexual acts, his warped view of masculinity:

I'm a man, and when push comes to shove, men will chose self preservation. We are ingrained with this illness, only the strong survives, so if a strong male is put in a situation that threatens his existence, livelihood, or manhood, we will retaliate with extreme prejudice to survive, those men who will suffer through it may not be too strong to begin with and is willing to just suffer through daily agonizing torture until they get over it eventually.

and gifting us with a glimpse at his internal monologue:

Am I wrong?? possibly! will I regret it? possibly! Can I fix it? possibly! that's the difference between you and I, answers to these questions are not possibly, I actually know the answers that applies to me, so that when it's time to pay the price, I don't have to blame anyone else, I can clearly say to myself in that moment in time, whatever I am and whatever I have accomplished is a culmination of all that I have done and if I'm satisfied by it then great, if not, I must live with the consequence as I am the only one to blame and no one else.

One user is pretty sure he is the one who got on his girlfriend's account and deleted her post, and that accusation is not something he takes kindly. Two other users state the obvious, and boyfriend is again displeased.

If you're not depressed yet, check out the full comments because he responded to pretty much everyone. Both girlfriend and boyfriend's accounts have been deleted, so this appears to be the end of the saga as far as Reddit is concerned.