AITAH for setting a deadline on my GF to tell her family about us?

I (34F) have been with my GF (40F) 3 years. We met 18mos after she separated from her ex-husband and the father of her kids. We were coworkers, got along well, one thing led to another and though we've had our ups and downs have been happy.

The problem is - nobody knows about us bar one faraway friend she sees every so often. When we first got together her children were finishing their final year of high school, and then they had 2 years further education before they would go to university. At that point she explained that because they'd been through major upheaval with the split, house move, etc, she did not want to disrupt their education further because they'd just got settled and important educational years were coming up that would shape their future. I could understand this, and agreed.

(It's worth noting I am the first woman she has been with - so I do also understand that this is a mass "coming out" and from personal experience (I have dated women all my life) I know it never gets easier, so I am very understanding of why she is so apprehensive.)

As time went on we started having conversations about when would be best to tell them, and everyone, and she suggested once they had finished those two years.

Fast forward to now. They finished their education 3 months ago, get their results in a few days, and if they achieve those results will be moving in the next 4 weeks. There is no sign of the conversation.

What's worse is that two months ago it was a milestone birthday for my GF. Her brother arranged a whole family weekend abroad to celebrate, and invited her ex-h because of the coparenting and how they are still friends. She agreed to it, and he went, despite me saying that it felt a little uncomfortable and that it did in honesty bother me to not be there.

The following week she then cancelled birthday weekend plans that we had as her ex-h could no longer have the children for the weekend, and she didn't want to say anything because it would "give it away" that she was with someone.

As the summer has gone on I've asked a few times times when she is planning on telling the children/everyone, but I've never had a concrete answer beyond "once they have their results".

Because of the events of the past few weeks, I've essentially run out of road with patience and I told her that if at least some family members weren't told by the end of this month, I would leave the relationship. I explained I couldn't stay when I felt I wasn't being publicly chosen after three years and when it felt like there wasn't an end in sight.

She reacted badly, accused me of threatening her, stamping my feet and being impatient and selfish by not considering her perspective or feelings and how difficult it is for her - which I do. It dissolved into quite a nasty fight, and she has been taking space for a few days.

AITAH? Have I just blown everything up through impatience?