Hi JJ, welcome to the family!
I have found this to be an amazing site, full of people with years and decades of experience in dealing with the issues you describe. It is the most caring and knowledgeable forum I've ever run across...
It sounds like your husband has undiagnosed BPD, which is very common. It is very difficult for a pwBPD to believe they have a problem and seek help. Unless he seeks help, from his own desire to improve, it is very unlikely your uBPDh will make progress from where he is. Fortunately, there are tools that can help you help him. This site is full of techniques that will help your communication in ways that will help him stay regulated when he gets emotional. The acronyms of the most frequently used techniques are to not JADE (Judge, Argue, Defend, and I always forget "E"), and to SET (Empathy). It is very important that you validate his emotions, but not validate his bad behavior. I highly encourage you to look at the training here, and also read through some of the posts. It is usually very validating to read other people saying in print something that you could have written yourself.
I recommend you read this article, it helped me understand what I was facing when I was in your position not that long ago:
https://bpdfamily.com/content/what-does-it-take-be-relationship
What steps are you taking to take care of yourself? Are you seeing a therapist?
Common abbreviations:
pwBPD - person with Borderline Personality Disorder
uBPDh - undiagnosed BPD husband
BPDw - diagnosed BPD wife