Any advice on my situation with my ex having Borderline Personality Disorder?

You made the right decision because you would never have any peace in your life. You have distanced yourself physically and legally, now getting over the emotional part takes a little longer. Let it go cuz she's going to be a camelion ALL her days and will make everyone miserable. Get into a positive state of mind and stay there. Be loving, gently honest and consistent with your son in ALL areas of his life...he doesn't need any confusion in his life as there is enough of it with her. Kids are forgiving and loyal even if one parent is a nut case. Focus on him and in due time (with a few disappointments along the way from her) he will figure things out for himself. Say a daily prayer for Perseverance cuz you will need to. Best Wishes. Been there.