She blamed me, she blamed our vet, she blamed where I live, she blamed the fact that she wasn't there. Everything except for whatever medical condition actually caused his death.
People with BPD tend to have no brakes on intense emotions, so anything small (to non BPD people) feels massive to someone who has not learned how to brake.
It's so often not even about you.
With my ex, and now with my SO's D21, who is bipolar/BPD, I think of them getting on a roller coaster. I can get on with them or I can stay rooted on the ground.
Over time it gets easier to stay put on the ground.
It's better for everyone that way.