What’s the worst thing you can say to someone who suffers from Borderline Personality Disorder (BPD)?
Nothing at all.
Let me clarify: Say you’ve been having an argument. You think it would be best to just go to sleep and leave things to cool off until morning. So you roll over in bed, turn your back to me, and say nothing. 
Or you’re texting, and things have become heated. You leave the last text from me just hanging there because you’re tired of the discussion and you don’t think there’s anything left to say.
Terrible move. 
Nothing is the worst thing you can “say” to me, as someone who suffers from BPD.
You see, when you have BPD, you don’t just “let things go” in a disagreement. You don’t just “get over it” when things go wrong. Seemingly insignificant things can start a spiral of self-loathing and despair that is impossible to overcome without excruciating amounts of effort. While you may think that just saying nothing is better than saying something “wrong”, it is actually the worst thing you can do. 
Without closure, the mind of a person with BPD goes into overdrive. First, there’s the anger. We have all kinds of things we NEED to say, to get them out of our heads so they stop circling endlessly in there. But you’ve made it clear that you’re done, so we can’t. We’re stuck obsessing over them for the next 24 hours or more.
Then there’s the self-recrimination. You hate us. Obviously, you simply can’t stand us anymore. We’re worthless. Not worth the time of day. Let’s face it, we’re sh*t. 
After that comes the bitterness and fatigue. We become so exhausted from the inner monologue that we shut down and spiral into depression. Nobody cares. What’s the use in trying anyway?
I understand that sometimes you walk away because you just can’t handle the drama anymore. Sometimes you have to walk away so that you don’t lose what little temper you have left. But maybe reading this will help you understand the effect it has on me. Walking away, turning away, not returning a text, giving me no closure, is saying, to my mind, I don’t care about you. I don’t care what you have to say. You’re not worth my time anymore. This relationship/friendship is over.
So the next time you’re finding yourself tempted to just let the sun go down on your anger, reconsider. Let us have closure. Please. It means the world to us.