I used to think the exact same way until I got into a similar situation myself. Not with a murderer but with a controlling sociopath. I am a mature, self-sufficient, intelligent, well-read and well-traveled woman of 44 years. I have a very good job. I am refined and have class. But what I also was? Naief (I don't know how to say it in English).
Someone like that creeps slowly into your life like molasses and it is barely perceptible how you bit by bit lose your self-esteem. They are predators who learn very quickly where your weaknesses are and preys on them...they chip away at your self-worth and you start to believe him that you are a loser and that you don't "deserve" anyone else but him. The stalking starts. He makes his suffocating behavior seem like love in the beginning. He's so concerned about you. Wants you to be safe. "Accompanies" you everywhere - even when you don't know he's there... then he goes through your telephone and text messages; he searches your wallet and your purse... he reads old agenda's and confronts you with relationships you had prior to even knowing him! He notes your kilometers and asks you why you drove 30 km. further on Monday than you should have. He makes you call him from work so that he can still hear colleagues (to make sure you are AT work) and keeps you on the phone until you are in the driveway.
The physical part comes later. By this time you believe that this is what you are worth. Where is the intelligent, self-sufficient, strong woman? What happened to her light? Her spontaneity?
This happened to me and I got out of it before he did something terrible to me. It took me two years of professional help to "get over it". What were my weaknesses? No children - he had a son (maternal feelings can been very strong). I was a young widow (26) and he used my fear of abandonment against me. I can see this now, but at the time I was blind. Even my family and friends could not convince me.
So that is how we get involved with men who abuse us. And out of shame, we don't talk about it nearly as much as we should. I hope that anyone of you reading this that is in a similar situation can find his or her inner strength and GET OUT.
Love and peace. Annalisa (from the Netherlands)