Women who choose abusive men may have learned that relationships are like this, from their upbringing.
Some women enter a relationship and at first it's everything they hoped for. They commit to their partners and acquire a home, possessions, pets and a life. They may become pregnant and research shows that this time can be the start of an abusive relationship. The woman is vulnerable and an abuser may seize an opportunity to start controlling her. This may be subtle to start with but can include criticising her, humiliating her and generally undermining her self-esteem. He will perhaps stop her from going out and seeing her family and friends, isolating her from supportive contact.
When the baby is born, the power and control often escalates.
Sometimes actual physical violence is used to control the woman.
A woman will begin to feel helpless and frightened. He may threaten to torture their pets and the baby if she doesn't do as she is told.
She may lose all her self-esteem after being told continually that she is useless, ugly, etc. She may begin to believe that she wouldn't cope on her own.
She might consider trying to leave but often he controls their finances, making it difficult. She may feel for her life and many women are actually murdered if they try and leave an abusive relationship.
She has her whole life tied in with her abuser. Her possessions, her home, her children her pets. Try and imagine just walking away from that.
I know the OP is in a better situation than some. However, I have tried to explain how living with an abuser affects someone.
I know someone who lived with someone who beat her. He held their baby over the lit gas hob and told her that if she didn't do what he said he would burn the baby. One day in a rage he stripped the woman naked, raped her with a glass bottle and locked her out of the house. This abuse went on for years. The children were emotionally damaged and a referral to social care was made by the school. Social workers and health care professionals became involved but the woman denied anything was wrong. This was out of fear for her life. Eventually everything escalated to the point that the terrified woman walked into Sure Start with her children and begged them to help her.
She was taken into a safe refuge and eventually was rehoused anonymously away from her abuser.
This account is just the tip of the iceberg. Just look up the statistics for domestic abuse, it's all there.
www.womensaid.org.uk/information-support/what-is-domestic-abuse/