You will find excellent communication skills, strategies, boundaries and more on our
Tools & Skills Workshops board. One skill - JADE (Justify Argue Defend Explain) - doesn't work well with most people with BPD traits (pwBPD). For them, they see the world in emotions and perceptions, logic doesn't work.
Better approaches are SET or DEARMAN.
Understand that she may not be able to truly listen to you due to her perceptions of the emotional baggage from the past years. BPD impacts most the closest of relationships. If she is willing to start and apply therapy - actually you, your spouse, the children would all benefit from counseling - she may listen better to someone with whom she's not in an emotional relationship.
The reality is that if she's determined to divorce, it will happen. It only takes one spouse and the family court will passively referee the process. Fortunately the children are adults and therefore there are no custody or parenting matters to complicate a divorce.
Let me add that your children too would benefit from counseling. Likely they've grown up in a home with discord and some level of discord, without insight and guidance they might otherwise be inclined to seek out adult relationships similar to the dysfunction they saw with their parents' relationship.