Hi TiredOfWalking and welcome to bpdfamily
BPD is a difficult disorder and can manifest itself in various ways. Not all people with BPD behave the same way and not all of them necessarily exhibit all the main traits associated with BPD.
I no longer have much of a relationship with either my stepdad or my sister) have lead to my mom having these issues that are now driving me crazy to the point of needing to see a therapist. Or is it possible that they all have BPD and my mom is just experiencing it in an unconventional way.
Do you have any recollection of how your mother behaved before she was married to your stepdad? Did she already exhibit any traits back then which you now would classify as BPD-like?
How would you say your mother's behavior has developed during her 28 year marriage to your stepdad? Do you feel like her behavior is becoming increasingly problematic or was it like this from the very start of her marriage?