Feeling the need to be protective of the ones you love is normal. Being overprotective of someone can be disfunctional, if it interferes with their life and motivations (i.e. if she gets mad at you for being overprotective... that may not be a good thing).

At the end of the day, she is a normal, able, competent person that, with or without you, can never be totally protected from the dangers of this world, BUT, you must trust her and her ability to protect herself from harm. Ultimately, she should not need you to protect her from situations where she may be hurt or killed.

This is just me, but I have this feeling that God did not put you on Earth to protect her. I don't think God would give any individual that amount of power. I think that's why your wife and therapist think you are delusional when you say that.