I can see your point totally, he is the longest standing relationship you have had and it is your point of reference for what is 'normal'
Then you see others through your work and see it is not in any way normal, let alone loving or supportive, which relationships should be.
People's responses here are showing you that life is not normally, as harsh and unkind as yours has been, but he is constantly belittling and scaring you and mentally manipulating you into believing you are wrong, we are all saying NO HE IS NASTY AND WRONG! You have not done anything to cause this.
We respond according to our life experiences, ie if my DH hit me even once, l would leave the same day even after 15 yrs of good marriage as to me it is so totally unacceptable to hit someone.
Also you talk about your poor decisions, but you have had to struggle so hard just to survive his abuse, you have made the only decisions you felt were open to you at that moment! Give yourself some credit.
Believe me we all make the most monumentally stupid decisions, we all get things wrong, the difference is you are not forgiving yourself, and accepting it is in the past and what matters now is the decisions you make today and tomorrow.
Nothing you have ever done, excuses or gives him permission to be violent and abusive,
Nothing you have ever said, has caused him to be violent and abusive.
He is violent and abusive because he chooses to be.
You don't have to live with it, OP you deserve so much better.
Do you not feel angry at him?