How do you keep the relationship going with your mother. I'm very close with our son and have always found it difficult as husband was always resentful of any attention I gave him. Of course, I wanted him to join in and us to be a family, but that never seemed to be an option.
Both my parents are deceased now. I think the relationship with my mother evolved over time. I gained more understanding of her BPD, and had empathy for her, and also learned how to have boundaries. How your son is managing now may also change over time.
You are in a similar situation that my father was in. In addition, you have a lot of influence with, your son, as he probably sees you as the "normal" parent.
I encourage you to read up on the Karpman triangle
https://www.bpdfamily.com/content/karpman-drama-triangle. BPD seems to affect the closest and most intimate relationships the most but I think children are next in line to closeness after the partner. For some reason (not a rational one) a pwBPD seems to feel threatened by the partner's relationship with other close family members. PwBPD perceive themselves in Victim perspective. The expectation is that the romantic partner take Rescuer position and whoever the pwBPD feels is a potential focus that might take away attention to them from the partner is in Persecutor position.
As a child, I was more compatible with my father. We shared some similar interests. My mother sometimes did show her dislike of this connection. I wanted my parents to think well of me, especially my father.
After leaving home, during visits to my parents, I complied with BPD mother, walked on eggshells. I wanted the visits to go well. Eventually I felt the need to have boundaries with her behavior- for my own children and myself. She got angry at me over this.
BPD mother pulled my father "to her side" and that changed our relationship. He passed away after that. I did keep contact with my BPD mother after this time and eventually stepped into the position of assisting her in her elder years- but from a distance (I don't live near where she did). I did visit her to the extent it was manageable.
You may feel you need to align with your H over your relationship with him, in order to keep the peace but know that he can't get his father's unconditional approval or love in the way a son would want that- but he believes he can have yours.
Your son is staying away for his own emotional protection. IMHO, the better chance of being a more intact family is for you and your H to work on your own issues first. Please maintain your connection to your son. He needs to know that at least one parent loves him unconditionally. Don't blame yourself for who his father is. I'm sure that you had no idea when you first fell in love. You are also doing the best you can with it. Trust that your son is too.
As to deciding to not argue with your H before you left - that actually isn't a bad strategy. I can relate to the arguing, the emotional drama, as being a part of the relationship. When I lessened my emotional reactions to my BPD mother- our relationship felt a bit more distant. But this doesn't mean your marriage depends on drama. You can learn to emotionally react less, not JADE, not get into circular arguments. You can learn other ways to communicate with him, to the extent possible.
