Welcome, lovenloathe. Sorry you're going through this; it's a hell most of us are familiar with. Love the candy covered poison analogy, very fitting. They should have to walk around with a "Mr. Yuck" warning sticker on so they're easier to avoid in the dating pool.
Regarding the 'correct path' I want to add my view - all please note that it is NOT meant to impugn Keep's decision to stay. There is no one clearcut 'right' answer to whether or not to stay in a BPD marriage 'for the sake of the kids.' We all make the best decision we can, and there can be more than one right decision in this issue. And only -you- can decide what's best for you.
For me personally, I'd rather get out of the toxic relationship
so that I can present a healthy model of personhood and interpersonal relating to the child. If I stay in the toxic relationship, that's the only version of human love and relating the child gets to see; they also, in that space, see me accepting verbal abuse from BPDh, and that's not a lesson I want to instill in them, that this is the way you're supposed to let other people treat you. If I get out, 1. I will be a healthier, happier person _myself_ all around, which is good for my child, 2. I won't be inadvertently sending the message to the kids that you're supposed to let people scream at and verbally abuse you, and 3. At some point, I'll be in a healthy long-term relationship with a non-disordered partner, so the child would get to see what human relationships are
actually supposed to be like, which is crucial, because it's what they see as children that they will seek out as adults.
Part of my reason for staying is simply access - my son is my stepson, and BPDh (biological father) will, out of spite, ensure that I never lay eyes on him again if I leave. If he were legally mine and therefore I could have joint custody if I left, I'd already be gone.
But then she can have these ever so brief and rare moments of wonderful honesty and vulnerability... .And I believe that if that person trapped behind the mask could wake up and take control... .am I falling for a subconscious trick of the disorder or is that a real plot where the real her could grow into the woman I hope her to be.
Yeah, most of us are living that fantasy. It's part of why so many Nons get stuck for years, or god help them, decades. People with BPD do not ever magically wake up one day and stop being the way they are. It just doesn't happen. Intense, targeted, loong-term psychotherapy is the only thing that can change them.
I can tell you that I've been on the conflicted fence for about a year; it can take time to pull yourself out of the emotional quicksand of being in love with a pwBPD. Keep asking yourself good questions, like the ones you are here: "isn't this the same thing I've been telling myself for the last 7 years? Is there actual light ahead? When do I leave "hopeful" and land squarely in "squandered". Is it a wasted life to spend it with someone ill that emotionally devastes me, tells me how easy I'd be to replace and begs me to divorce her... "