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I guess my struggle at the moment with moving on is the idea of not waiting, but still thinking about them, and ultimately wanting to get back with them when they're able to.
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Are they diagnosed BPD?
What are you hoping for? You're posting on the detaching and learning board, but it sounds like you're really not over them...
It's up to you what you want to do, but it sounds like she moved on - perhaps to someone else - without looking back. If you want to reach out, I don't see any harm in that; the worst she can say is "No" or "do not contact me" right? Just don't have any expectations, and realize if this person ditched you so easily over "feelings" once, they can do it again, even if they seem receptive to rekindling the relationship. It sounds like you fall hard for people, or at least you did for this person, so harden your heart a bit if she (I think you referred to "her") does open the door.
This part though:
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To provide context, my now-ex had a stalker situation escalate, and it made them feel unsafe to be around someone of the opposite gender like myself, meaning they no longer had capacity to be in a relationship anymore, and needed to focus on themselves to improve things in their life.
The hard part for me is that they clarified I had done nothing wrong, and that we both loved each other an incredible amount, but couldn't be together right now. Leading up to this, there was clear evidence that a "split" was potentially on the cards, noticing a shift in their behaviour and being harder to reach, which was difficult for me to navigate.
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How much of what she said are you sure about? If someone I was in a relationship said that to me, I'd probably just move on. Even assuming she's being completely honest and forthcoming with you, indicting an entire gender over the actions of one (1) person shows a lot of emotional immaturity on her part, and a need to grow up.
And that's the best case scenario. if - on the other hand - she's NOT being completely honest, and some or all of that is made up, well she just revealed that she would play games with your feelings & could discard someone she supposedly loves for no reason at all.