When I got into an argument with him (which wasn’t about relationships or anything of the sort) his big comeback before he blocked me was to tell me how Sh0eonhead thought he was "cute".
It was literally a completely unrelated point to anything we were arguing about.
Do not read "walking on eggshells". It's basically the Bible of doing shitty things to people with BPD.
I had a very bad experience with a borderline - she stalks me across the Internet and posts all kinds of lies and half truths to paint me as an insanely horribke person. But equally out relationship was a horrible co-dependency mess of love and hate that dragged on longer than it should because no one would end it. However that was a mutual issue because we both had mental health issues that didn't mesh.
As long as you communicate openly with a borderline partner and explain your anxieties or emotions and make an effort to understand them (I highly recommend anything by Dr Marsha Linehan - she's a doctor who has BPD herself and basically revolutionised how it's approached by clinicians). I had a very bad experience but trust me if I can still vouch that good relationships with BPD sufferers are very possible and very rewarding as long as you're prepared to make a little bit of effort in communication. That's all it takes.
Now I'm gonna have to message a mod because my ex will likely see this and either comment with nonsense and inspect-element screen caps or try and get me banned from here.