Barry Natchitoches
It sounds like he.... was going to mate with your wife. Peacocks let out a "special shriek" while they are doing a "mating rush" at the peahens. It is done to let the peahens know his intentions, that is, he wishes to mate her.. the peahen either accepts by squatting down to be bred, but if she is not in the mood or does not want to mate with him, she simply remains standing and moves out of the way. And that's the end of it. He backs up and continues strutting. It happens very suddenly and can be startling if not expected.
The horrible scream getting closer really matches this mating rush behavior. He's the lone male and he was excited by seeing something crouching. He didn't mean to attack her.
Not to discount what happened to your wife.. it can and does seem very scary when one doesn't know what is happening, and that mating rush call is very weird and loud but it likely is case of misunderstanding of his intentions in that incident.
When peafowl mean to attack.. usually they are quiet and approach you sideways.. maybe flicking wings once/twice- this is meant to intimidate/warn and if not back off they FLY up at you. It's extremely clear. I have ever seen fighting or aggressive peafowl scream or shriek exactly the same time they go to beat each other. Sometimes they will honk/yell during a fight session but it has always been during a break when both are standing a little bit apart.