hello and welcome seekingpeace143,
You've take a good step in reaching out and posting here. There are a lot of members who have been where you are now and have a wealth of experience to share.
to simply answer your question:
I need help or advise on how to present to her that she (we) need help if we are going to continue.
you move slowly. very slowly.
now for the longer answer. for most of us here, when we found the BPD answer, we felt enormous relief, and maybe a touch of excitement. a desire to immediately share our early information with the idea of 'now things can start to get better'. more than a few members have done that, only to find our partners not receptive or even down right angry. which of course is understandable. no one takes well to the news of I've found out what is wrong with you and how you can fix it. its a bitter pill to swallow. many people with mental illness are resistant to therapy.
you've made a good step in seeking out a therapist. make an appointment and go yourself. its important to have as much support for you. professional support is crucial. in this you can model the way for your wife. be honest. keep it simple. don't get trapped in endless discussions with your wife about what you are doing or why.
you said it may not be safe for you and your wife to stay together? can you say more about that?
how does this sound for an early approach?
'ducks