Look at actions, not words. I had a very close friend who had BPD, and I believed everything she said 1000% and she was 1000% convincing and I was 1000% convinced. And the truth was...so, so, so shockingly far away from anything that I believed. And in retrospect, had I looked at her actions, then I could have protected myself more.
She probably loved how I made her feel, but I don't think that she loved me. Maybe she has BPD but also some sociopathic traits. I don't know. I don't think all people with BPD are such a way, but I would be careful because your story does remind me of her some. She would have various guy friends who she would act and pretend with (or she was acting and pretending with me). It was like a chore to her...to manage her social connections. I remember how she told this one guy that she wanted to see him so badly but couldn't make it because ____, then she turned around to me and expressed that she really didn't feel like going.
I feel so insanely betrayed and abandoned by her. She treated me like shit when I reached out to her for help because I was feeling suicidal. We were on good terms at the time, although she had been acting extremely strange and extremely distant, and had been spending a ton of time with a guy friend that she told me she "was not interested in at all." Well I reached out to her, extremely kindly, probably one of the most polite and kind "please show some me some support I'm feeling suicidal" messages ever. She just gave me a bunch of shit and refused to say a single kind thing even when I made the suggestion. She never apologized. She never visited me in the hospital, or after, even though she pretended to want to visit me. She lied to my family and friends while I was in the hospital. She painted herself as a victim and as a good person, and I lost my whole group of friends of 7 years over it. I was extremely supportive. Of course...I never hit her, and I never yelled at her, but I feel like it needs to be said just to make it clear.
It's so painful. I have days that I regret not having killed myself. I am only alive now because of the people in my life who want me to be alive, and because my dog needs me. If it wasn't for that then I would just as soon be dead. And sometimes I try to convince myself that I should be dead anyway.
I suppose the only good thing that came out of it is that through various mental health care efforts I've been diagnosed with BPD and am now just starting to receive treatment. It's also sad to me that I don't treat my friends even a fraction as well as I treated her, and yet they are infinitely more caring. One friend of mine, who herself had BPD, and who I had abandoned once in a way I'm not proud of at all, ...she cancelled work and spent two days in the ER room with me. And she didn't want to date me or anything. She didn't want anything...she just cared.
Look at actions, not words. I think there are certain people who are extremely dishonest, and they know how to misrepresent their emotions. They might love how you make them feel, and they'll use those intense feelings to convince you that they would take a bullet for you. But you might not actually have value of your own to them. My friend who stayed in the hospital with me, and visited me in the psych ward every time (long drive, short visits), she clearly valued me as a person. She showed it in her actions. My other friend, who I was extremely supportive of, treated me absolutely horrendously and did not care at all once she no longer needed me.
I don't think it's fair to judge others based on bad experiences with one person. That's why I'm telling you that I just hope you are cautious and skeptical, and look for the actions because they will tell the truth. I hope she really is a good person but I'd be horrified if I didn't at least suggest a better litmus test than "she sounds convincing." I'm sorry. I don't know what to think...