Hello
FwdBkwd101I, too, am a grandparent and I relate to parts of your story...enough parts to know your hurts.
Our grandchildren are now 28/30 so this has been a long, long hurtful journey for us. In the early years we were surrogate parents to these two loves-of-our-lives as our daughter went from one drama to another that included broken relationships, custody battles with each of their fathers, etc., etc., etc.
Oh, there were good times but without warning the shoe would drop and we (mainly me...her Mom) became her targets. Many, many times we took the verbal blows...waited for the dust to settle...then jumped on the roller coaster again...because we didn't want to be cut off from our grandchildren. In those early years their eyes lit up when they saw their Gramma/Grampa but as time went by they were influenced by their mother's role-modelling in relation to us. Sadly we have no relationship with them now...but even sadder is the fact that they do not have relationships with either of their fathers nor those families. Even sadder? There is no closeness between the two of them. This is the epitome of dysfunction. My heart breaks for them!
You ask, FwdBkwd101, if you are fighting a losing battle as you work at staying close to your granddaughter. My advice to you is to try not make it a battle. The one to suffer the most will probably be your grandchild. Do what you will, spaced within reasonable timing.
(With due respect to
BenFranklin (post above) I do realize that every family situation is different. Sometimes more drastic measures have to be taken and that was the case there.)
Your son, indeed, is in a bad position. That was nice of him to call you after the family visit to apologize. Obviously he respects you. With that said, he is making a life with his wife and his child and, fingers crossed, that grandchild of yours will be able to grow up without having to live with her parents separating.
Yes, it is heartbreaking to have that dream of togetherness not come about. Over the years I have cried buckets because of the same dream not becoming a reality for me. I was late in finding the path to my healing...my serenity (a work in progress!). I had to learn to look reality in the face...then start working on ways to better deal with what is...IS.
You have certainly come to the right place to voice your hurts, know you are not alone...and...to learn about BPD and how to better communicate with someone who suffers from it. Arm yourself by learning some of the "tricks of the trade" you will find on this website (with links to more). For sure this is a journey...will take work on your part...but it is altogether possible that your relationship with your DIL will gradually become more harmonious...and the one with your grandchild will stay intact. Time well spent.
((HUGS)

from one grandparent to another.
Huat