Jeff... . Jeff... . Jeff

Be careful my friend. I cannot count how many potential relationships my exBPD ruined BEFORE we ever dated (and while she was with someone else!) If it was some cute girl working at the mall in a different city and she knew I was going there to see this girl, my ex would actually leave work early and call me that she wanted to meet up for lunch/shopping - thus *blocking. Months after she left me and ran into the arms of another guy, she made sure to get a distant friend of hers to stop talking to me after seeing some pictures of us together online. Literally, this girl has never spoken to me again - despite us having arranged to go out again! LOL
BPD's have abandonment issues and engage in magical thinking. There is nothing more magical than thinking you can still have a relationship with someone you deeply hurt - and without accepting full responsibility (which includes accepting your issues and actively engaging in therapy to correct them). Additionally, even when they abandon you, there is still this need, want and desire for them to feel as though you are not completely out of their life. They
must have that to avoid feeling as though they will be alone. We can label it things like a safety net, recycling or something simplistic but in truth it's very complex and ties into how the disorder works. Does it mean it's manipulation? Not necessarily. Does it mean they do care about you? Not necessarily. Often they do care and aren't consciously trying to manipulate but it will typically feel that way in the end. These are still troubled souls who haven't learned appropriate and mature ways to cope with their emotions - and it is very difficult for them to learn to do that.
So, knowing those things, is it a shock that a BPDex would suddenly contact you (or anyone else they dated) upon learning information which suggests you've moved on and may be permanently out of their life? No! It makes perfect sense, doesn't it? It's completely understandable given the issues they struggle with. However, we have to remember that those issues are still there and the reason their behavior changed is only because the situation changed that it triggered abandonment within them. The apologies are often sincere
in that moment. Most BPD's
do know they hurt people they cared about. Most feel awful because of it and the self-loathing and shame from that feeds the disorder even more. But you have to remember: The moment they feel you are secured and/or they feel too attached, you'll be pushed away again. That pattern will remain until they are in recovery.
You have not healed from the previous relationship with her and it feels like you don't fully understand the relationship dynamic surrounding this disorder. That concerns me greatly because if you were to re-engage your ex, when she inevitably pushes you away again, I worry that you will be further traumatized by that invalidating act.
I have not been with my exBPD for 19 months or so? I've gone out with plenty of women but I still have a knee-jerk reaction to flee the moment I sense or see any emotional neediness in them. If I see insecurity or anything I now recognize as a warning sign I ignored with my ex, I instantly hit abort!
I think you should consider avoiding one-nighters. I don't feel those are ever helpful. That's typically about void-filling and avoiding intimacy and I assume what you really want is a person with whom you can have true intimacy while feeling secure and respected? Those people are out there (albeit difficult to find!). Don't screw up your path by misunderstanding what is occurring with your BPDex. If you truly want to consider the possibility of a relationship with her and she's attempting to make it happen, set a minimum amount of therapy she will need before you can pursue it. If she complies with that, you two might have a chance. Otherwise you're just going to scratch the scabs off your still sore wounds.
I would go back to NC, continue working on your healing and being open to finding someone who can offer you the healthy relationship you deserve. And I wouldn't hesitate telling a potential partner about what you've been through. If they're decent, understanding people, they'll understand the need to move slow and careful - which should help you see that they are different than the type who hurt you.