After reading your post, it is clear to be that these mistakes happen because we take our husbands/wives/partners for granted, because we think he or she would never do something like this. I don't condone affairs, they shouldn't happen, but I can see why they happen. I am going to stop taking my DH for granted, I am going to make him feel loved, liked and wanted.
Then if I may say so TimetoAsk you've absorbed the wrong message from this thread. The OP has said nothing about her husband not making her 'feel loved, liked and wanted' - just the opposite in fact, and yet this STILL happened.
As it does, to people in perfectly good, loving marriages. Because affairs like this aren't about someone's marriage.
You'd be better off having a conversation with your husband about how you as individuals can protect your own fidelity. Just having a good relationship won't provide that protection.
I'm also sorry to see the thread go this way and that the OP hasn't come back.
I don't think it's just people who've been on the receiving end of infidelity who have responded harshly - and some haven't AFAIK.
I think there are responses from people who feel frightened by a thread like this, because it shows that if a happy person with a strong marriage can do this, anyone can. And there's not a damned thing you can do about it, because you cannot control your partner's behaviour.
So I think fear is a motivation for some of the harsher posts. I hope the OP takes that into account as a possibility and doesn't lose sight of the other advice she's been given.
I'm glad she was brave enough to start this thread. She writes about an affair a lot of people like to believe doesn't happen.
But they do happen and they are happening more than some people realise, to ordinary couples in good relationships.