Hi BP,
There is a lot to read on this site that can deepen what you've read in the book. Here are few places to start if you like!
The Do’s and Don’ts of a BPD RelationshipSETI think couple's therapy is not necessarily recommend. That can be tough on any couple, but I think it can be difficult for these kinds of relationships. But the good news is there is a lot that you can do just on your own to help learn how to, if not make things better, at least not make things worse we say!
Oh, you get defensive? Oh, then this is your tool, man!
Don't JADE. I started using it early on. I memorized the letters asap so I could recall/use it when things were pretty extreme at home for me and it helped a lot! It's one of the best things ever!

How are you doing? What's hurting you the most in all of this?
Again, glad to have you with us! You are not alone! We understand how hard it is!
with compassion, pearl.