Best friend of 15 years is punishing me for a scheduling conflict. Am I handling this right?

My best friend (let’s call her N) and I have known each other for over 15 years. We’re both 30. A few days ago a conflict escalated between us that I can’t stop thinking about, and I’d love an outside perspective.

What happened:
N announced in our friend group chat in April that she was planning a pilates event and asked everyone to keep the date free. Honestly, I had forgotten about her message. This week, I invited our mutual friends to an evening at our place, something my partner and I had plans to do for over a year as there’ll be a big fireworks display we want to watch together. It turned out both events fell on the same night. N commented in the group that she didn’t think that was cool we invited everyone on that same day.

When N announced her event, I should have immediately told her I already had plans that evening. I didn’t do that. I apologized sincerely, but with the caveat that I wasn’t apologizing for having planned my own evening, but for not giving her a heads up sooner.

Where it escalated:
N called my apology “half an apology” and demanded I call her to apologize “properly.” When I said I was happy to talk, but calmly and on equal terms, things escalated quickly. She called me “cowardly,” threatened that she knew “how to interpret” my behavior, and posted in our friend group that she would no longer participate in group activities until I apologized “properly.”
She then blocked me and told me I could reach her by SMS when I was ready to apologize.
The following day, she invited everyone in a mutual friend group to her housewarming party in February on my birthday, this will be over a year after her moving in. She tagged everyone individually, including by BF, except me.

I now sent her a WhatsApp message explaining why I didn’t follow her SMS demand, that I don’t feel treated as an equal in this situation, and that I’ll reach out when I feel we can talk calmly.

Backstory:
This isn’t the first time N has reacted this way in conflicts. A few years ago, I had a conflict with her that led to us not having contact for an entire year. I don’t remember what the cost was, but after our conflict she posted in her Instagram story “I’d rather lose you than the argument”.

I feel like I am subjected to her power games, even though I feel her disappointment in me as valid. However, I struggle being treated this way by my best friend.
We both have very different personality types. I usually try to avoid conflicts by all means, and she usually loves to argue. I feel in the past we’ve gotten along as long as I do everything to keep the peace.

My question:
Have I been handling this the right way? And how do I move forward from here, both with N and with our mutual friend group who has witnessed all of this?