Hi klm72791 and

I am so sorry that your mom has placed such a burden on you and I am glad you are here to get the support you need.
My mom has been diagnosed with chronic depression and OCD. Doctors have also mentioned manic depression and schizophrenia but have never actually diagnosed her as such. I firmly believe that she has BPD. She has all the signs
It is common that pwBPD are often diagnosed with other mental disorders before BPD is finally identified. You state that doctors considered schizophrenia. What evidence did they provide to support such a diagnosis?
I can't have a real conversation with her, because once I say anything that is somehow about myself, she will change the subject to something about her. She always blames my dad and me for her problems, and when I try to set a boundary, such as not being able to visit because of a busy schedule, she will tell me that I am a horrible daughter and that "I sure will feel guilty when she passes away and I haven't seen her".
This sounds very typical of BPD behavior. Also you mentioned that mom doesn't have any friendships or close family relationships. This also seems to be a hallmark of pwBPD as they tend to run off anyone they get close to. Not to say that these can't also be indicators of other mental illnesses.
There are so many things from my childhood that I either remember clearly, or vaguely, that enrage me and bring me to the point of hating her. I know there was emotional and verbal abuse. I remember one or two times of physical abuse and I have a strong feeling that sexual abuse occurred as well. I do remember her thinking it was funny to show relatives how we could "make out" and I remember my one aunt threatening to take me away after a display.
This is disturbing that your mother had you pretend to "make out." Have you spoken to a professional about the abuse and your suspicions? One of the most challenging things for a child of a parent with BPD is to take care of themselves. We were trained from a very young age to think of our parents needs, to the exclusion of our own. Because of this it can lead to years of feeling guilty for not wanting to take care our parents needs and a feeling obligation to do so. Have you read the article on this board Fear, Obligation, and Guilt
https://bpdfamily.com/portfolio-parent? Most importantly, what are you doing for yourself right now? I understand the need to know how to deal with mom, but the best way for you to learn new ways of interacting with mom is to heal from the abuse.
I would also suggest that you read the article, also on this board, that deals with emotional incest
https://bpdfamily.com/portfolio-parent.
I want you to know that you are among friends here. Looking forward to hearing from you.