Could it be the start of Alzheimers?

I would not be bothered.... I swear my mother would go through as BDP... cause one day she's nice and the next day she's a cow.... through the years I learned... mummy a cow = angry at daddy for not jumping when she demanded, then she calls me and takes it out on me... now I simply ignore it lol.... oh she never apologize

You just need to get self confidence...if you know you did nothing wrong, then let SF rant and rave and forget about it... you know you are doing things right... why do you feel bad cause he says you can't do anything right... pffff

be like a terrier... barking and biting will never work, rather pee on it and walk away

Is it possible you may be projecting your own father's mental illness on your stepdad?

Diagnosing others can be problematic, because if you convince yourself there is something "wrong" with them mentally, then you begin to look at them solely through that lens you've held up to them. Not saying we are necessarily wrong in doing so (since we can be correct in our assessment)... I'm just saying there can be other reasons for his behavior other than bona fide mental illness.

Acra brings up a case in point - perhaps he has something organically wrong with him. Or maybe he is more self-aware than you think, because it sounds like he is sometimes nasty to people and then follows it up with periods of "praise." To me, he may be a person who is self-aware and when he realizes he hurts others he then tries to fix it by sending them compliments.

I would suggest having a heart-to-heart with your mother and see if there are other strange or troubling behaviors. Perhaps a check-up is in order for your stepdad. Likewise, if other employees are feeling his behavior is unusual or progressively getting worse, then someone in a position of authority should have a sit-down with him.

Our BM has BPD (diagnosed by a psychologist) and my grandmother had it. You have to remember that it's really hard for them to control it--the part in their brain that dials down emotions is just not there, so no matter what you do, they will always exhibit symptoms. Slight insecurity becomes full blown screaming jealousy, a little happiness with someone means they fall madly in love, a little anger become "I hate you for all eternity"--someone says something offhand and if they care, it suddenly becomes either the best or worst thing they ever heard. Some are aware of it but they still have difficulty controlling it. Think of it like schizophrenia for feelings except there are no medications to help it.

This is one of those mental illnesses that even therapists have a lot of difficulty with because it's hard to mentally separate between them having a "choice" to hurt people and them not being able to control it, since they do have a train of logic that ends up making them make those decisions.

Then in order to cope and control their environment, they manipulate and gaslight because it's the only way they can feel "normal"--so much that they often end up believing they are right because they drive everyone else into a tizzy.

Borderline is one of those mental illnesses that we have not found a good treatment for. I think the closest thing that might help is cognitive behavioral therapy so maybe look into that.

I feel sorry for those who have BPD (Even though it seems like they are doing everything on purpose, but they're actually like a car that has started drifting in the snow--the driver turns the wheel the other way really fast, sending the car into an even greater wobble, in order to fix THAT they swing the wheel again, finally sending the car into a spin--they're trying to fix their environment but keep making the wrong decision.) but for the regular victim of their actions, it's usually better to stay away and ride their waves instead of trying to stop them. You can just prepare yourself that they will be emotionally exaggerated and that their actions have little to do with you and everything to do with their inability to cope.

Pardon me but don't you mean bi-polar? He sounds pretty straight forward hot and cold. A Borderline will plot and scheme and lie and manipulate and manage to play the victim at every turn. Yours sounds like he swings from one pole to the other in a rather efficient manner and absent all the curlicues and fakeries of a Borderline.

In any case, you are taking the right track to move on with another job. You can't change people, why try. It's your mother I feel most sorry for. She is stuck with him. At least you have the choice to walk away.

A more softer and perhaps effective way would be for a check up with his Primary Care Physician. IF he agrees

Leave it at that with him. When he does schedule an appointment you could call the nurse and tell them your concerns.

IF he becomes a danger to himself and others unfortunately, calling the police may be the only way. He may be placed in a 72hour hold where he will be watched and checked out by psychologists and physicians.

You cant make anyone seek treatment and/or take meds as much as you want to. Are these new symptoms he is presenting? If so, it could be age related such as dementia or gosh forbid that A word.

So sorry.....this is just sad any way you look at it. Doesnt sound like BPD--they could care less how they act and they blame others. You said HE said he doesnt know why he does what he does....NOT bpd. He is taking some ownership.

there are many resources for bpd families but the one with the disorder needs to get diagnosed. this is one of those personality disorders that dont often admit theres a problem. be aware that npd can also co exist with bpd. that might be the reason for the cruelty.

i wish you the best of luck.