To be sad this is how I found out DS is engaged

Genuine question...how did you want to find out?

Sounds like he was!

I’m going to guess if you’d been up and replied you’d have got a phone call straight back.

However, most adult children have at least a bit of awareness that phoning in the middle of the night and waking the parent up jumps them to ‘there’s been a disaster’. So we test the water first before late night or early morning phone calls.

Really pleased for you, and that your son has found someone that both he and you are so keen on.

Enjoy celebrating when they get home.

Thank you, what a constructive contribution to this thread.

As you've said, they did nothing wrong ("How was she thoughtless?!")

So, there is clearly no reason to assume that the mere mention (without any accusation or recrimination) of already knowing the news would make the couple feel they have done anything wrong, surely?

Remind me never to start a thread in AIBU.
OP, I do not think your DC will go NC or get married without telling you. The drama on here is insane.

What makes you think the OP is fixated?

I can't imagine many mothers not being at the very least a bit put out about finding out about their child's engagement via SM rather than in person.

But that applies to OP too. Why is knowing in advance so important?

Sounds like if op hadn’t fallen asleep she would have known before instagram too.

Oh I wouldn’t have mentioned it. You’ve made them feel bad because they simply forgot his sister follows in insta and because you fell asleep before midnight.

It sounds like they were excited to tell you OP, it's a shame you found out through social media and the time difference wouldn't have helped either. IMO, it would have been nicer if they had told family first before announcing to the world, but it sounds like they were genuinely excited to tell you the news. I'd just let it go, hopefully they'll be more mindful in the future with any other big announcements.

Because she now has two feeling bad on their happy day and apologising to her.

Her son called her pretty soon, she could have just waited.

I totally get your heartbreak here OP. I've not been able to read the full thread as I've got terrible signal so only the first page will load. Try to give them the benefit of the doubt as you don't want it to come across as the start of MIL trouble (which is honestly when mine started resenting me).

To share how a very similar situation turned out (a crazy and unbelievable story)... BIL went travelling with a group of uni friends and his girlfriend of 3 years. It was one of those schemes where they get the experience of different cultures and working to improve their living conditions. He went the digital detox route and only wrote to his parents every month or so when he'd get to a new village, only ever saying what work he was doing, nothing personal (which was normal for him). I'd been following one of the girls on the trip and updating the family about what places they'd been to/what they were building etc then one day she posted tagging his girlfriend saying how beautiful it was to see her bestie getting engaged in the most magical of settings. I messaged to pass on our congratulations and then phoned DH to share the news. It wasn't a huge surprise as it was always on the cards. Half hour later I went back online and saw the next posts - photos of the girlfriend indeed getting proposed to except the one down on one knee was not BIL! We found out she'd been cheating, they separated while out there and he went with another group while she carried on. The new fiancé was actually his uni friend and had been doing the dirty behind his back for years!

At the expense of taking the shine off a couple’s happy day.

OP could have just waited a few hours, her son did call her.

I can't comment on you and your mum, but in relation to the OP's update, that's nonsense.

Why not mention it, if there was nothing wrong with posting on Instagram and no need for the DS and GF to feel bad?

Why mention it though? What did it achieve?

I'm sorry OP but, very gently and kindly, I wouldn't be surprised if they end up marrying in secret just the two of them and two witnesses. Really sorry to say that you've already made all of this about yourself and your feelings - and it's just the engagement stage! Just to say that this is exactly what my mum would have done and that's exactly why I got married in the local registry office and only told her six months later. Cannot stand the meddling and the drama - and this had red flags all over it. Again, I mean the above gently.

Ah just saw he messaged but didn’t say it then, yes I’d be hurt but honestly maybe with the excitement he just forgot

Agreed.

There was no need for OP to tell them she already knew.

But she’s got them apologising to her on their big day.

@PeppyGreenFinch well that’s what OP wanted. So on the happy day of their lives they now feel bad about something. What a fantastic congratulations that must have been for them

How was she thoughtless?!