I do think that
now is the time to get the 'dispute' addressed in court. Even though it wasn't part of the order, it was a longstanding pattern. It worked. If you wait a long time and tell the court "a year ago I had additional time" it may not give you a hearing ear.
I believe it would be good to seek not just for that time to be restored but even more time than she had allowed you. How about seeking
at least equal time. More and more courts are granting that. Courts are more likely to make a decision somewhere in the middle. If you only ask for those hours on one day then you might get it, maybe. But if you ask for a lot more time,
and give reasons for it, then even if you don't get your entire request, you could very well walk out with more than those 7 hours she just cancelled.
As for why she is doing this now, it almost surely is connected to her not depositing your most recent child support checks. Did that occur to you? Maybe someone reminded her that she was giving you extra time and so how could she claim you're a deadbeat father, hmm? Oh, and this... .
My ex just got engaged and has turned back into a complete nightmare towards me, the hate machine has started up again towards me which I don't understand. She just got engaged, shouldn't she be a little happy?
Remember, most pwBPD view all ended relationship partners as abusive and the evil scum of the earth, lower than whale poo. She's idolizing her New Guy and so of course you're now the opposite, Mr Evil Personified. After all, she can't get you out of her life since you two share a child. That doesn't mean she won't try.