In-laws holidaying close by

You say "unknown to us at the time" except the cynic in me is going "Really??? They really had zero information that you were leaving to go to the Canaries on holiday...no idea at all???" and then if you dig a little deeper, you will find that your DH let something slip during a conversation. Something that he would have thought of as a throw away comment and not at all important but actually it would be a nugget of information to his parents who would have latched on to it and booked as soon as he was gone from their home.

They are definitely giving me those sorts of vibes to be completely honest with you.

Actually op I don't think they are as lovely as you think. They chose to have only one child and have now taken over yours too. I would have a huge, huge problem with that. That is completely disrespectful of you as a mother and even a wife.
They come bearing gifts but that is just a layer of manipulation. How calculating to appear in the same holiday destination as your family. They sound insufferable and suffocating.
And to be honest, children absolutely adore anyone who's showering them with gifts. So I wouldn't feel guilty about that relationship.

You've had to endure 20 years of them, unless you want to endure another 20 you need to give your husband an ultimatum about them. You're sacrificing your place in your family and as a parent, because they have decided that's their role and you are a bystander. I would be utterly done with all of them.

I’d be full on telling your Dh he either moves back in with them or he sets some very firm boundaries. Turning up 10 miles away is appalling. Trouble is, you’ve tolerated their behaviour for 20 years so they’re going to be very resistant to a change in dynamic. Decide what you want eg no more joint holidays, no ‘dropping in’ from 40 minutes away, birthdays are sacrosanct and stop with the over the top presents and tell Dh he MUST enforce these. If he doesn’t, it sounds like you’re likely to break and then there’ll be a big rupture from which they’ll be no coming back. He needs to explain that it’s all too much, not you.

As a pp mentioned, this living on the never never of ‘They may not be around for much longer’ is bollocks, they may be around for another 20 years!

This bit in your last post @ineedsomemoremetime "They are almost 'elderly' now though and DH now refers to 'we may not have them for much longer'. Good genes run in his family though and I can't live with that mentality. Could go on for another 10+ years and by then the children will be adults."
leads me to believe that your DH is mired in the FOG - Fear, Obligation and Guilt.

Fear that 'we may not have them for much longer'....well, I hate to be blunt but your DH or you could drop dead just as quickly from an undetected condition or be knocked down by a car or bus or whatever (I'm not trying to be crude here but merely outlining that no one knows when their time is up).
Obligation - that if he doesn't spend every possible moment with them he'll miss out or the kids will or they will. He's obliged to be there for his parents, all the while his wife and children miss out on being a family of their own.
Guilt - that if he doesn't spend time with his parents, what might happen to them but there is no guilt associated with not spending time with his wife and kids away from his parents.

What does 'almost elderly' mean? Are they in their 60's or 80's? Are they fully mobile and has anyone sat down with them to discuss their care plans for whenever that might be necessary as you might end up seeing even less of your DH or it might turn that they would be expecting you to step in and care for them. You will need to put your own boundaries there.

If you let this pass and he try's to placate his parents over this you'll spend every next holiday/family day out on high alert waiting for them to pop out from behind a hedge.

Sorry, but this did make me laugh!

YADNBU
It's about time your DH set a firm, and I mean film boundary in place with your PIL because it sounds suffocating.

If that is not possible, don't mention anything online or in person to any family members about where you will be spending your next family holiday.......then hopefully you can all get the break you deserve.

I don't think your DH's mother understands she is full on and the effect this is having on you, she needs to respect your space and your DHs as well as show some respect, if she blames this shenanigans on you, do not stand for it and make sure your DH backs you up100%

@LookItsMeAgain - as much as I agree that the pils are too full on and dh ought to re-examine the current dynamic, I don't think dictating his relationship with them is a goer.
She can't tell him what he is and isn't allowed to discuss with them. Nor can she set the bar for a 'need to know' basis. That's control.

Dh's mindset on this has to change, not his actions. Anyone should be able to tell their parents where they are going on holiday or other details of their family day to day life.

The chat needs to open up a discussion about the level of involvement and their presence, not what he can and cannot do.

From where I'm sitting it reads as though your DH is less comfortable in saying No to his parents than to you.

How did they know where you were going to be when you're on holiday? That's where I would start.

Put them on an information diet. Only what they absolutely have to know about what is going on in your lives is what they are told about.
"Yes we're going away on holidays"
"No, we haven't decided where but sure it's going to be an adventure for the kids".

You need to get your DH on side. I wonder if he'd be the type of person who would go to his parents for support if you had a medical condition and would share your medical condition with them? If he would, you need to have a very grown up conversation with him about what is and isn't suitable topics of conversation with his parents.

Does your DH have many friends? Just wondering.

How old are your children? As they get older they will make their own friendships and be going out. Childhood holidays don’t last that long, Our oldest is 17 and we’re not sure how long he’ll be coming away with us as a family so don’t let the holidays slip by with your in laws inserting themselves into them.

With all the birthday celebrations, if they are yours and the children, why not invite your siblings and family as well. This would dilute his parents and turn it into a family event. They can choose what they want to do on their birthday but not yours!

Ahh, my MIL is a bit like this, but she has the good grace (and perhaps good sense) to realise that if she pushes me too far I'll relocate the entire family to outer Mongolia and she'll never hear from us again.

(Her piece de resistance was actually locking us out of our holiday accommodation so that we'd be forced to come join them at a bar after we'd snuck some alone time in one holiday - ironically she prevented us from trying for the grandchild she desperately wanted!)

It's late to start, but you need a very firm hand with your husband in this OP. He sounds like a people pleaser, and because it's been so long, there's no reason for anyone to think that you're not ok with the arrangements.

But I'd actually go one step further and organise a surprise long weekend for just you and the kids. It sounds like you would really benefit from feeling centered for once.

Do NOT tell anyone where you're going!

DH explained lightly to his parents why I wasn't there and now his mum is upset and affronted.

Did he blame you entirely? Or say, "it's our family holiday and we want time alone"?

Your PIL sound like nice people overall, who care about their son and family. The fact that they are quite wealthy and can afford to do what they want perhaps gives them a feeling of entitlement. Sorry I haven't read all the messages, but if he's an only child, it will feel more intense. If they have lost a child in the past, this could also add to it. Personally I would have a 1:1 chat with your MIL, making it clear how much you love them and its not personal, but sometimes you feel you need some time just as a family/ couple. The present suggestion of 1-2 pius savings in the bank is good.

I'm also curious as to what your dh's thoughts on their involvement are. You don't really say, other than he thinks it's normal.
In some families it is normal...if maybe not for most.

Does he enjoy spending 24 hours a day on holiday with his parents?

Yes it sounds intense and overbearing if it's not the sort of holiday you want to have. I wouldn't like it - all time spent together. How exhausting, NOT relaxing.
They clearly enjoy it though and probably imagine you do too.

You might well get some fireworks now, huge offence taken...drama and upset. You sound reasonable and diplomatic so I'm sure you'll handle this thoughtfully.
Calmly stick to your point. Good luck. Don't envy you. x

It's really hard to set boundaries further on, and sometimes people won't like you for it, but you need to think about how you want to live your life and discuss with DH.

@ineedsomemoremetime

It doesn't sound like they are jealous.

It just sounds like they think it's ok to drop by anytime, wherever in the world you might be.

And they think this because you and DH have allowed them to. You haven't put any boundaries in place.

So now, when you try to put boundaries in place, of course they are going to feel affronted.

So, exactly how does your DH feel about all this? Does he share your feelings?

Because your DH is going to be key in changing all this. If he doesn't feel the same then it'll be much harder to enforce any boundaries you want to put in place.

Absolutely this. Is she trying to make herself a victim? Where is her self awareness? She should be cringing at the realisation she has just crashed your holiday.

YANBU. The time has come to decide. Will this continue forever...? Or are you going to make some changes.

Changes will probably involve your MIL being further upset. That's OK. It will make a change from you being upset.

It will probably also involve DH having to choose between happy wife or happy Mummy. Time for him to cut the apron strings.

This is not ok. My DH showed signs of this (blaming not visiting his parents on my full schedule, when I thought it would be a good idea to see them), and I addressed it with him. It was easier to blame it on me and he did not consider possible consequences.
This way, he's perpetuating the idea that he and his DPs are a unit and you are the outsider.

He does have to address it with them, honestly but with love. The way it's going, it might result in a complete breakdown of the relationship between you and your ILs, and it needn't. They are good GPs to your children and at some point, the children will develop a relationship with their GPs that you will not need to facilitate. It is in their interest to preserve the relationship, but on terms that are acceptable to you.

It sounds unbearable.
Your MIL sounds bossy.
Taking offence?
Let her. Maybe cause a huge argument and refuse to see them.
I would rather never see them than allow them take over my life.
Your husband is selfish, doesn't care about how you feel.
You have chosen badly.
He threw you under a bus but now you need to run with it.
You need to be a lot firmer.
This is your family and your life.
They do not get to take over your family life.
Ask your husband does he want to return home and live with his mummy?
Let him go would be my advice.
Selfish man.
Stop tolerating it.

You need to ensure that they don't know where you are. He must have told them.

As far as gifts, set up a savings fund for each child and explain you are trying to make sure they have sufficient funds for university when they are 18 so appreciate contributions to that rather than more than token gifts.

A good compromise is one joint holiday and one individual holiday