I am not surprised that you don't know many things abot Mom's life before she met you. She did a lot of damage to me both emotionally and financially in that time.
First, she did not make being my mother her top priority. She always made me feel like I was not her pressing priority, including by living in New York, where the cost of living is, and was, very high. Too high in fact for a single mother to make ends meet with a teenage son to clothe and feed. So she turned to me to make money from my having summer jobs, and not putting mey earnings into a separate account for me later, but using then to keep her going. She did that in this first case in my memory with my earnings from the Adair agency, wherre she first introduced me to modeling and being in the public gaze of adults, and resulting in my developing a bulimia-like illness from which I nearly died, while I was trying to enter my freshman year in college.
Then there's the matter of her abortion, which she got while married to my first stepfather, Joe Keating. I did not know that she was getting an abortion because my stepfather told me that she had an ulcer and was getting surgery for that. I did not know about the abortion until she told me about it in a light-hearted tone, saying "Remember when I got that abortion?..." She then said that she got that for me, irresponsibly making me feel responsible for the killing of my little step brother or sister.
She had been a virtual poster child for the rightwing's sterotypes about women using abortions as a means of birth control: a married woman, employed in her own business, who just didn't want the inconvenience of having another child, because it might interfere with her career.
In addition, my mother had some very fishy relationships (with Robert Ross, David Sachs, Robert Feinberg, Richard unknown, the owner of the Hotel Tudor, - tellingly located on East 42nd St - to name just the ones I know of.) Mom embarassingly had the hotel's address put into Choate's facebook even though she did not put any money into my education, only undermined it. She also showed me a card that she wrote to David Sachs, in which she said how much she loved David's newborn daughter, and "how much Daddy loves her, and how much Adair loves her, and how much her mother loves her too," (as a side note). In so doing, Mom was bragging about sleeping with a married man whose wife had just had a baby. David Sachs at least had the good sense not to accept the card, which is why Mom still had it in her possession for me to see. During this era, Mom generally wore so much "on stage" make up that my friends at Choate commented on it, saying she looked like a prostitute.
Now, when my mother says that she loves me and fully supports me, I know that's not true. She could start the long road to rehabilitating our relationship by putting some, as they say, money where her mouth is.