Hello and welcome, ohiojayhawk!
Whew, you've got a lot to deal with. I've got a few answers for your questions.
1. This all sounds consistent with BPD, including the lack of risk-taking behavior. Not all pwBPD are the same. That said, I'm not a clinician, and if I was, I couldn't diagnose anybody based on a description from a third party.
What is more important is that these traits match BPD well enough that the tools and lessons you will find here in this community should help you better deal with her, whether it actually is BPD or not.
2. Getting her to get and accept professional help is difficult, and getting her to keep trying is too.
3. When do you remove your son? That's a really tough question. If her r/s with the son isn't rapidly changing, I'd suggest you sit on that choice for a bit longer.
Let me ask you some questions.
What kind of support do you have for yourself? Do you have family members or friends you can trust and talk to?
How long have you suspected BPD?
Have you read any of the Lessons here? This link is the full list of them:
https://bpdfamily.com/message_board/index.php?topic=287068.0And last, and most important... .you mention suicidal tendencies and thoughts... .
Is this ongoing, or is it occasional? And most importantly, is it happening now, or happening more now?