I know what you mean!! I used to be afraid to reach middle age, because it seemed all my family, aunts uncles etc, went into deep depression in middle age!
It happened to me at the age of 51, oh no, I was going like the rest of the family! I've fought antidepressants, counselling, and any kind of help, because I was determined to beat this thing. I Have been on antidepressants now for about a year, after trying to kill myself, and am quite resigned that there must just be an inbalance of the chemical needed in my brain, due to family genes history. I too had deep shameful feelings, but I thought that came from all the abuse as a child. Now I know that if I was a diabetic, I would have to take insulin for the rest of my life, but because my brain lacks something I am not producing, I need 'insulin for my brain'