I agree, I never stay anywhere where anyone has ANY reservations about my being present—see no upside, only downsides. Agree it’s awkward if your H wants to go. I’d write a lovely note thanking them for their kind invitation as well.
I may be missing something, but no formal invitation was made to the OP. The husband of the house-owning couple texted the husband of the OP. If that’s the extent of the invite, I think if anyone would be writing any sort of thank you note it should be OP’s husband to whom the invite was addressed. Seems odd and frankly a little sexist to assume OP - the woman - would overhear an invitation she didn’t directly receive yet somehow be expected to write a lovely thank you note.
I’m actually a big thank you note writer, so the issue isn’t that nobody should be writing any TY notes, I just don’t see why the wife of someone who receives an informal text would be the one tasked with writing a note. Guess I’m just getting tired of people assuming the wife is responsible for all the heavy lifting of managing social affairs. OP’s husband is presumably a functioning adult with a hand and the ability to write - let him write any note that needs to be written since he’s the one that received the invite.
Yeah, I wouldn’t be able to relax and enjoy that vacation, at all. I’d be waiting for the other shoe to drop. Not worth it.
@milee30 I think we are of the same mind. I asked my husband to text his friend and say thank you, but that we are unable to use it.
The OP mentioned that the couples used to be close, but now only the husbands are. Sounds like something happened along the way with the wives…so of course she’s uncomfortable doing this. A whole hearted offer is one thing, a reluctant general offer from one party is another. Sounds like your husband is pushing this and his friend is trying to comply. No way am I doing this, he can feel free to go on his own.
Vacation is to reduce stress, not add to it.
I would say no in a heartbeat. Now. Married 36 years and much clearer on things.
15 years ago I would have felt damned if I did and damned if I didn’t.
I probably would have reluctantly gone and we would still be having words about it now LOL.
No way. Can you imagine if you accidentally broke something, or if something went awry and it wasn’t even your fault? Nope.
I’m in the minority here, and think it’s fine to accept the invitation. The fact that the husbands have remained close and the wives haven’t seems irrelevant; things evolve and that’s ok. The fact that the wife might have had reservations about loaning out the house also seems irrelevant; apparently the couple has jointly decided to move beyond that.
I’d take things at face value. The offer was made, so I’d assume it was sincere and would accept if it sounded like a good vacation destination.
It is so stressful staying at someone else’s house leveraged by your DHs relationship IME. Just don’t do it. DHs like this are IME clueless, and quite often won’t be part of the work involved in keeping the pristine house pristine. As above this whole thing falls on to the wife because the DH doesn’t even think about the minutiae.
Not a chance.
Run away!!!
So do you go to your H now and say “CC voted and you lost.”? 
I’m among those who say no. I have a second home and we happily lend it out a lot. It’s rustic and there’s not a lot to mess up, but even then it always means extra work to have someone stay there. Invariably something gets left in the fridge to rot or something gets broken or misplaced. I would be very stressed out to stay in the new home of someone who wasn’t wild about lending it out.
@goug78 NO WAY! But I sure appreciate an anonymous forum where I can get different perspectives!
@2mrmagoo be sure to update us!
Nope. No. Nope. NO. I see no good outcome here and truthfully, it it were me, I wouldn’t find it a relaxing time knowing that I was not really welcome in their home.
@2mrmagoo - Communication is usually better than speculation. Have you considered asking the wife if she feels comfortable with her husband’s offer?
If the wife was ok with it she would have texted/emailed/called OP. I imagine she probably reluctantly agreed to it.
@oldfort - Pure speculation. What harm can come from OP reaching out to ask?
“What harm can come from OP reaching out to ask?”
While that approach appeals to those of us who are direct, it could be considered rude to some people because there may not be a polite, truthful answer. When faced with a direct question, “are you comfortable with us staying at your house?” some would find it difficult to politely answer no. It’s unfortunate, because it would be much easier and sensible if we could all ask each other directly how the other person feels, but the reality is that many people will be uncomfortable with the question and struggle with how to phrase an answer. Especially if the truth is unpleasant. Almost nobody is going to directly reply to someone else that they truthfully don’t want them in their house because they’re messy or they smell or they clip their toenails and leave them on the coffee table. Instead, most polite people will struggle to find a diplomatic answer or defer to the expected answer “of course you are welcome.”
IOW, asking people directly about how they feel about uncomfortable or awkward issues is unlikely to generate an honest response and more likely to increase the awkwardness.