I guess some people think that slagging off a person's husband is unhelpful, but slagging off the third party is supportive.
I've seen people slate the OM to someone while being more careful in how they refer to the wife, too. The thing is, you can alienate the person seeking help. Love and loyalty don't have an off switch. It's not support if the person concerned walks away from the threads because the commentary is too distressing. And I've seen that happen more than once. NOT saying that justifies attacks on most OW/OM, either - I usually stress that I don't think it's reasonable to blame the person who owes you nothing but common decency. But in this situation I do think the OW has something to be blamed for. It's horrible behaviour.
Having said that: OP, the last things you type do make it clear that he has lied through his teeth about the scale and nature of their relationship. I really do think you need to tell him to get out right now, not shillyshally seeking decent accommodation. Someone's sofa is fine for him right now. More than he deserves, in fact. And how on earth did he leave keys, license and wedding ring there? That's not stuff you are absent-minded over.
I also just saw this:
Quoting laws at me (like we're in A Level Law class!) is pointless by the way. Advise OP on her DH please and stop waffling about the police
You're giving a victim of harassment wholly incorrect legal advice with blithely huge certainty, and yes, that needs to be challenged. You were wrong. And the A level comment is really rather uncalled-for. In point of fact, I can assure you that my legal studies went considerably beyond that level. Which is why I don't as a rule offer legal advice, and always recommend recourse to qualified solicitors.