My biggest concern is protecting our son from the parental alienation happening.
Have you found any resources to offset things psychologically? My go-to books were Divorce Poison by Richard Warshak, and Don't Alienate the Kids: Raising Emotionally Resilient Kids When A Parent Has BPD by William (Bill) Eddy (who also wrote Splitting: Protecting Yourself When Divorcing a BPD/NPD spouse). And then anything by Dr. Craig Childress, who isn't the easiest writer to read but is the first professional to link together what he calls pathological parenting (BPD) with parental alienation. He also has some good youtube videos.
I hope this isn't too much of a firehose of information

Depending on how severe the alienation is, there are also some excellent insights from a formerly alienated child (now adult) that you can find at
https://ryanthomasspeaks.com/I was curious about your relationship with your son because the nature of the bond does seem to determine outcomes, not to mention the amount of time he spends with you. Childress unapologetically refers to alienation as child abuse and is trying to get it codified as such. We have a long way to go but it's the first big step in the right direction for families like ours.
Do you have kids?
I have one son (18). I divorced his father in 2010 so we're coming up on a decade post-split. His dad was a former trial attorney who ended up representing himself. After four years of chronic litigation, I ended up with full custody. S18's father is no longer in his life. It is hard to call it a victory when there is so much damage and trauma in our wake. At the same time, I am surprised at the relative resilience my son has developed in response. A good therapist has made a world of difference, as well as me learning to validate his feelings and help him learn to identify what he thinks and feels, versus what his dad wanted him to think and feel. This support forum has been a game changer. I cannot imagine how things would've turned out without the input from friends here.
How are you holding up? Representing yourself must be taking a real toll. Does your ex have representation?