I don’t want her in my house

And there's absolutely nothing to suggest that the ex has any desire to look round the house, let alone "nosy" into anything. The OP thinks the kids will insist on showing her. She might well be completely bored by the whole process.

I wouldn’t dream of going round my ex’s house and nosying into his and his partners bedroom and don’t know why you’re even contemplating it. I don’t feel the need to see the kids rooms there either but I suppose I would if they really wanted me to.
Put your foot down you’re not being unreasonable at all not wanting her there

A quick tour of the rooms downstairs, or their bedrooms is ok, I can imagine she wants an image of where her kids are sleeping when they are away from her, but maybe ask if you can have a tour of their mums bedroom if she sees your bedroom? See how that goes down. Not very well I would think.

That’s really judgy and nasty to the OP. Her wellbeing is important too and no one is going to die / come to any danger if the kids have to wait a week or two to show their new rooms off to their mum. It’s doesnt need to happen NOW, the op gets to have some say over her home space!

Exactly, as a mother I would want to know what my kids other room looked like whether unpacked or not. More importantly the kids need to feel connection between both their lives, having their mum see their Dad's new home is going to make them feel securer. I actually feel sorry for them having a step mum who is more concerned about showing off a clean house than caring about their well being.

I’d invite her in for a cuppa and try to be friendly.

Many years ago, relatives and friends would be shown all round a new house. Round my way, that no longer happens - you see the living room/lounge, bathroom and kitchen. That's it.

There's no need for the children's mother to see anything outside the living room and the children's bedroom[s].

Having said that, my husband's kids were adults when we married. Latterly, we supposedly got on better with the ex. However, she could still be quite sarcastic and was quite prone to barbed comments. (I was told by a mutual acquaintance that she was even like that at secondary school...)

Family circumstances meant that I did see the living room in her home and I thought that we were having a better relationship. I felt sorry for her - her Affair Partner died unexpectedly and then she lost her next partner to illness - but then the sharp tongue appeared again. I told DH that under no circumstances was she ever to get over the threshold of my home.

I think that you're stuck in a more awkward position, OP. If you have to let the ex into the house, make it clear that she only sees the living room and children's rooms.

Hand her a paintbrush!!

I would never want my ex coming in to my home and I would never expect to visit his. In surprised at how many would!

Could you not drop them back to her this week? Save the tour for once you are a bit more organised.

We never got through the door. Even in the depths of winter and it was below freezing, icy, snowy etc. We found out what the kids rooms were like when they put it on the market. Their new home was taken offline as soon as their offer was accepted, so we never saw the new house.
Tidy your hallway, let her in there to collect her children, or you drop them to her this week and avoid it?

I would think about the kids - it’s important for kids to be able to share their lives with the people who are important to them (such as their Mum’s).

i would worry if you don’t let them show their Mum their new room they will not feel as if it is their home.

and as someone said above, if you don’t know her, this is a good way of building a relationship with her - and making the kids happier.

Can't you look at it the other way?
You're letting her in before you've arranged the house to your liking, so she won't be the first to see it as you want it to be.
Save that privilege for your family.

I'm with the others. grant yourself the gift of not giving the tiniest shite about it.

Be cool. Let it go blah blah.

I had stepchildren and the first thing I realised is you have to suck up so much absolute crap as a SM, it's unbelievable. Go with the flow though as the day will come when she will need you to do her a favour and on and on it goes. This will not even register long term.

When I was with my ex, I was Cruella De Ville according to his ex wife even though they had divorced long before I met him and she didn't know me. Then her cat got a grass seed in his eye and that's my day job. I sorted it for nowt and ....suddenly I was a decent human being.

Mal et bon. Bon et mal.

Life is so much easier and a lot more pleasant when you aren’t so dramatic about everything.

Unless she’s a horrible person, let her in, make her a coffee and let the kids show their mum their rooms. Say ‘sorry about the mess! You know what it’s like the day after you move in!’. Say no if they try and show her your room. And then go about your day having had a perfectly uneventful, normal and polite interaction with a woman your husband co-parents with. Why all the fuss?

Why would you do this? Its very bizarre. Did she come into the old house and see where they slept?

Why would a dirty messy house be the best time for the dad?

Absolutely this! Unless you’re on really friendly terms then why on earth would the ex want or need to come in?

It might be the best time for their dad whose house it also is?

Have you ever had a tour / show around of her house? I highly doubt it.

just say no, yes the kids are excited but they don’t always get what they want and you aren’t comfortable with it.
just say you’re not ready for visitors yet but once rooms are sorted you’ll invite mum round. Then the excitement will have worn off and you can decide what you’re comfortable with.

@Doornon
I get you. I remember moving once and my actual bedroom that I had to sleep had all of my clothes piled on the unmade bed with boxes covering the floor I couldn't even find my toothbrush.
If someone had wanted to see that room at that moment I would have told them to fuck off. And I do find saying that does cause offence.

She's not a visitor. She is looking at where her kids are sleeping. I don't think she is judging you. Everyone moves - you're overthinking it.

It’s not the best time for the OP, and that’s perfectly alright. The kids can be explained to that the house will be shown when it looks nice.

If you don’t want her in your house don’t have her in. DSC mum doesn’t have to see their rooms or the house it’s not her house, they can always take pictures to show their mum, it’s ok to have boundaries around your home.

IMO the best way to manage this is very easy breezy.
Let her pop in, apologise for the chaos and say the children were so excited to show you round. If you don’t entertain her she won’t feel comfortable staying. Then as she leaves, apologise again and suggest once you’re settled she can pop round for a cuppa. (Note this could be an empty invite).
I suspect their DM feels just as awkward.