As far as posters being unable to offer calm and measured advice, hmmm, here's the thing.
When you post an original post that has within it a direct statement that you don't want to hear certain things, it's actually quite useful and direct, which helps. But it's also useful because it very clearly says, this is off limits, I don't want advice on this. Everyone has a right to that.
But this is only going to be for one of two reasons, one is that the poster is immediately defensive and protective because she secretly knows there is way way more that she's not addressing about the situation and she doesn't want to hear that, she wants, fundamentally, to push forward with the road she's most comfortable on even if that's temporary, or ultimately damaging or delusional. That's fine, that's everybody's right. But it's hardly surprising that people might assume the worst when a defensive posture is immediately adopted like that. If a poster were really genuinely happy with how she and her husband were dealing with the situation, she'd be unlikely to cordon it off, but to shout about it. So yes, some people will make assumptions.
The second option is that the poster has a fair amount of contempt for mumsnet responses and does not trust the majority of people to give good or helpful advice around it so doesn't want to share that stuff. Fine too, but in which case, it's also hardly surprising people would bridle at the implicit insult and the choice to post here.
It's totally fine for the OP to cordon off that for discussion, but it's also inevitable that will create what has been created here, since one of the above is true. And because of course any experience of affairs tells you advice without context is useless.
OP, the only thing I'd suggest is look at a good many threads here because, as I'm sure you know since you're pre-empting advice, there's absolute reams of evidence as to what is important in the wake of an affair and how years of people's lives and relationships are ruined or saved by correctly ascertaining the truth of what is going on, and acting on it, rather than brushing things under the carpet (the worst option) or relying on what they might wish to believe. We're here for us when you're ready, if you need it. Please do come back.