Hi again.
What you are dealing with here is very frustrating, yet common in a lot of the relationship conflicts we talk about here (unfortunately). I don't say that to minimize your experience, rather to let you know many of our members have learned how to respond better or are learning to deal with this sort of interaction right now.
It is as if he is protecting himself by holding on to his convictions.
I think this is a good observation. He could very well be seeing this as a threat to himself and is reacting in ways that protect him and his perceptions. It happens. He feels threatened and will fight back. Most people do that when upset, and BPD traits will make it even more likely to get this sort of reaction.
We talk about something here called Don't JADE and have a great article on it here:
https://bpdfamily.com/message_board/index.php?topic=139972.0 JADE stands for justify, argue, defend, explain. When we do these things, it tends to further escalate the conflict and create even more obstacles to communication. In addition, it puts us on the defensive making it seem like we actually have done something wrong. See if you think Don't JADE will help you here.
I understand the desire to defend and stand up for yourself. Been there, done that. It is hard not to when being blamed. The thing is, it only furthers the conflict and makes me more miserable, frustrated and upset. We talk about the tools as helping the pwBPD and the relationship and that is all true. I also look at the tools as a way to self-care and protect myself in these very stressful situations.
See what you think and then we can talk a bit more about it.
Hang in there. this al takes time and practice to learn.