Hi @naakrakeb , and welcome!
Sometimes, long wall-of-text posts don't get answered, but for me it's ok because I use text-to-speech (read-aloud extension)

It's very nice that both of you were friends before and could talk about everything. That makes it a good start for the relationship, because you both got to know each other before getting intimate.
However, this is a very dangerous combination: her having BPD and having cheated back on her exes and you having insecure attachment. Honestly, it doesn't look like this will end well. Because it is clearly impossible for you to fulfill her needs, and it seems like eventually she will need more than just you. Being awake all night long to help her out by phone is definitely something I do not recommend. It sounds like going too far and committing yourself too much for someone with whom you aren't married yet, and I don't think it is helpful in the long run for either of you.
Be careful about the stories you were hearing from her. She was portraying herself as a victim, but even if she is being truthful, that's still her side of the story, seen through her BPD lens. Was it really always them who took the first step in cheating? Did she regularly provoke them? Why did she need to cheat on them as well, instead of just breaking up the relationship?
In the beginning of my relationship with my wife, she would keep talking to exes while in my place and did it so freely. And she added an extremely sexy picture to her profile on a social messaging app, in which she was showing her back in a bikini, and it was like the kind of pictures that prostitutes use. Also, she proudly told me that she had cheated on all of her exes. I then asked what she wanted from me, if she wanted a closed relationship, and she confirmed it, so I got confused. Little did I know, it was all pure provocation, and in reality the cheating stories were fake. But I took it as real, so I thought, "Well, at least she is being honest with me, and that's what matters." My solution for that was to propose a one-sided open relationship. That might sound crazy, but we actually signed a contract on paper specifying the rules.
For me, cheating is the betrayal, not the act of getting involved with someone else. In open relationships, being with someone else is allowed, within certain rules. The book "Sex at Dawn" has helped me a lot to understand that and change my way of thinking about relationships. It turns out that she never got to use her right to be with someone else and confessed her lies. But the simple fact of having made her a concession at the beginning gave me some comfort, because then she wouldn't have a reason to deceive me.
By the way, I have already experienced an open relationship in the past, and it was splendid, with zero issues ever. Because she had excellent emotional control, like me. I felt very involved and kind of in love but didn't have plans to build a family with her, because my attraction to her wasn't strong enough. Yet, sometimes I fantasize about having her as my secondary wife in a Y relationship. I fantasize that they would be close friends and that my stable secondary wife would help me to remain positive and joyful while handling the BPD wife (the primary one).
The book teaches us that most human couples weren't monogamous until the advent of agriculture, which began to split people into small nuclear families, creating land as their inheritable property and, moreover, instituting the concept of marriage.