I've heard great things about The High-Conflict Couple: A Dialectical Behavior Therapy Guide to Finding Peace, Intimacy, and Validation by Alan Fruzetti.
Setting limits is always a good thing...sticking to them is even better. NEABPD is having a webinar next week on DEAR MAN- which is an effective way to handle a request/problem. I highly recommend it! https://zoom.us/webinar/register/WN_8FJXFIXfR8Wp_aCXkU4o8w
Hi u/interests_stuff! Happy to recommend some additional resources. To learn more about BPD, we would recommend you check out the "resources" tab on the National Education Alliance for Borderline Personality Disorder website. To learn more about DBT (we're biased) but think our podcast is a great place to start learning the skills ;) If you are looking for a self-help DBT workbook, we'd recommend this one. Finally, r/dbtselfhelp has a lot of educational resources and recommendations, including other books and workbooks you can check out. Hope this helps!
A great free book coming from a buddhist perspective is Mindfulness in Plain English