I wake up feeling depleted and hopeless and small.
I’m not surprise you feel this way. It is frustrating, I share your frustration. It does demonstrate how effective the BPD approach can be at bending the truth. Triangulation is one of the clearest ways of seeing this, where they paint one child bad and one good. They have to bend the truth, to keep this fantasy alive.
But time will out. You can’t fool all of the people all of the time. But we took a long time to realise about the BPD theory, so it’s normal for your husband will take time seeing it for what it is. But you’re right it is very frustrating.
We’re unlikely to win playing a BPD at their own game. They wear us down, wind us up, and then we react in a way that makes them look like the injured party, by snapping. Totally understandable behaviour, but we need to avoid J.A.D.E. (Justify, Argue, Defend, Explain) as if we do the BPD has got the rise they want. And we look like the guilty party.
Sometimes it’s better we show rather than tell. So you might want to demonstrate to your husband how a BPD can not accept responsibly for their bad deeds, by asking your sister for an apology the next time it’s appropriate to do so. Or possibly sit down and watch some movies with BPD in them, and your husband may then see patterns of behaviour. But in fairness the reaction you described was quiet natural, I’ve done it, we’ve all done it. So having had time to reflect, how will you be approaching hubby and sister on this ?