Hi DreamerGirl,
I'm sorry things feel so bleak at the moment. Looking at his situation, his extreme rejection sensitivity is in full swing -- he has been kicked out of the relative's home, and left behind someone in bad emotional and psychological shape. He learns he can't live with you. It's not surprising that he is easily triggered at the moment, especially with the additional stress of his living situation up in the air.
Looking at your situation, it was a healthy boundary to tell him he couldn't live with you. And you asserted that boundary despite his pressure. It sounds like you feel some guilt, even when you're together, and guilt can make JADEing very easy to fall into. Have you tried
validating questions with him? I found the questions to be be more effective than straight up validation statements because they bought me some time when I felt my feelings heating up. Plus, the validating questions do a better job of putting the problem-solving skills where they belong.
One of the consistent inconsistencies in someone with BPD is the roller coaster of emotions. Our job is to figure out if we can be the emotional leader in these relationships, regardless of where on the roller coaster our partner is at any given moment. This applies across the entire spectrum of the relationship, whether it feels like it's "on" or "off." Often, the relationship is "off" because that's one way for them to express intense emotions.
For us, we often we make significant decisions about the future of the relationship when we are running on empty. What can you do now to preserve your psychological/emotional health for right now? This will help you get to a better place for making decisions.
I found it was helpful to set up boundaries in advance, when things are "normal," and then, when things devolve, I can call on that boundary. That was an important way to preserve my psychological/emotional health so I could carve out enough strength to fill the shoes of emotional leader.