I empathise. It’s horrible watching your friend do this & for her to dominate your husband’s attention. It’s quite seductive of her & boundary crossing big time.
The thing is (& this isn’t giving them a pass on it) but men can be so oblivious to it (or claim to be & will then call you the jealous/mad/unreasonable one aka gaslight you if you say anything. Even if he is largely innocent - but clearly receiving it.
My fear is that by stopping the friendship & requesting him not to continue with it either - it causes them to want to continue with it more - or it prompts her to contact him independently - as it sounds like both will not want it to stop??
Can you talk with your DH? Explain the way she was acting etc - boundaries etc & get him to see?
It would be better if when she stays he then assert very clear boundaries himself of including you in the chat, very clearly not letting her monopolise him, kind of not being so flattered by it basically - but sending back signals that efforts to “seduce” aren’t working & won’t be entertained. I don’t know if you’re tactile with each other but for him (not in a PDA OTT way) to show sone gesture of tactile affection to you (arm round waist while getting something from the table or subtle touch) in front of her - naturally -so as to show her with his body language where his loyalties lie.
But how do you get him to play ball - as he’ll more than likely be completely in denial about it / may claim not to have noticed & /or get defensive or annoyed at your observations - esp if it is innocent on his part (& he just views her as a really close & old friend).
Def don’t think he should be taking time off unless you’re planning an actual activity or event when she’s coming & it’s a social outing.
By having him around in the evening only or after work may only heighten her efforts as she will know she’s only got limited time with him - so may make a bee line for him.
But she will be too flattered I think if she learns he has taken time off for her & she sounds a bit dangerous.
Maybe you could quiz her one to one on the state of her marriage, get deep & personal about her life & find out if she’s secure in her marriage. Every time she asks him something intimate - interject & turn the question back on her? Don’t let her dominate in your own home or lead things.
Horrible however when you have to consciously do power play with someone who is meant to be a friend. Is that really them friendship any more? Wouldn’t be for me.
Or insist her OH come as it’s rude to socialise as a 3 without him?? Call her out jokily & say how much she hogged your DH all pm last time & obvs needs her hubby there too??
Let us know how it goes 🤞