I just re-read that entire post and honestly, he was a young guy that processed things in a very healthy way. Better than most of us.
First, let me say welcome to the family. Every single one of us arrived under the same circumstances that you found this site, so know that it's okay to not be okay. We've all been there and had no idea where to turn. It doesn't make any sense, because mental illness doesn't make sense.
I'll echo what Forever said, there's not a perfect person on this planet. We all make mistakes, and we all mess up. That's not what should define us though. If you love someone, you forgive them and work through it together.
Let's dive into your post. She's pulling and pushing, she can't make up her mind, and she says contradictory things all the time. What's true and what's not?
Well, it's all true IN THE MOMENT. Think about hitting your finger with a hammer. It feels like the world is ending, the pain is extraordinary, yet ten minutes later most people have completely recovered from it. BPD is a lot like that because the person's emotions are all over the place when they're unstable and they're lashing out due to emotional pain.
She loves you- that's true. She hates you- that's true. She's just being fully transparent in the moment depending on her feelings. And feelings constantly change, so what she said 10 seconds ago could be a lie right now when she's in a highly emotional state. Yet it was true when she actually said it.
Does that help or make things more confusing?
Let's move on. What can you do? That's the million dollar question. You mentioned that she's living with your parents, which has to be awkward at the moment. Will that change in the near future? Because it would be very difficult to go no contact while also having a relationship with your parents.
Here's what would be helpful for you to learn. If she's screaming or depressed or super excited or anything in-between, it's because her feelings are out of balance. When you see this, it is not the time to talk about life decisions. You can ask her if she wants to grab lunch or go see a movie when she's unbalanced, but you can't ask her to start dating again. Make sense? You save the "real" talks for when she's neither high or low, because that's when she's thinking more with logic and less with her emotions.
Second, when she's disordered (another way to say not her normal self), you're there to help her through the moment and get back to her normal baseline. If she's sad, cheer her up. If she's angry, calm her down. This sounds ridiculous at first but you'd be amazed at what a difference it makes.
For instance, if she accuses you of something that's not even close to being true, the natural reaction would be to defend yourself, to set things straight, to argue and demand an apology. But for a BPD person, they're just releasing pent-up emotional energy and they aren't truly thinking about anything that's said. That's why you don't fight back, you don't take it personal. If she's mad, help her calm down.
If you want to give it one more try, then you must learn to communicate in a different way. You must understand where her feelings and confusing words come from- it's mental illness and nothing more. She's sick, she's unstable, and if you love her then you'll learn to understand what is actually going on within her mind. It's heartbreaking, to be honest, and I can't imagine living my life with those types of destructive circular thought patterns.