IIRC he confessed because he didn't want his wife involved more than she had to be. A real WTF for me, because. how can he recognize the hurt it would cause his wife to have the police do more investigation into his case without his direct confession, yet he has no concern for the women he killed,
I don't see a contradiction here.
To an extent, we all view those closest to us (friends, family, spouses) in more rounded and complete terms than distant acquaintances or complete strangers. Our nearest and dearest are fully-fleshed in 3D, accompanied by reconstructions of their internal, mental lives and shaded by capsule biographies of their pasts; those we merely know in passing or have only functional interactions with tend to be dealt with in far less detail, and thought of them only in the moment, assuming they have pasts and futures, but rarely delving into the details; those on the periphery of our mental worlds are mere sketches: unless we make an effort to take a realistic view of them, they are nothing more than composites of recognised traits, reduced in meaning according to their negligible roles in our lives.
If that's a 'normal' perspective, imagine the perspective in extreme: I am the sun around which all turns; my family and friends are satellites who owe their existence to me; all else is mere dust. In this case, Williams viewed his victims as scant more than objects to fulfil his desires. Is there any evidence that any of his victims were known
well to him? That he had genuine relationships with them?
I do find it uncomfortably interesting when individuals turn up who are clearly 'insane' in one context, but able to compartmentalise their insanity so that it doesn't bleed through into other areas of their comparatively normal lives.
I recall that one of the common complaints with Bomber Command air-crew in the war was the hideous juxtaposition of the enormous strain and terrible deaths they encountered at close quarters by night with the daylight world of normality they would wake to back on the ground. A man watches his navigator burn to death over Essen, the plane limps back home and he awakes in his bed that afternoon to an angry note asking why he hasn't paid his grocery bill or remembered his auntie's birthday. Many men found this dissonance extremely psychologically taxing, and more than a few 'snapped' in response.
To take the matter to the personal, when I have a problem preying on my mind, I become highly ineffective when it comes to other tasks. There's far too much psychological 'bleed' from one situation to others. From long experience, I've found it better for me to 'hit pause' on regular life (as far as is possible), solve the issue that is troubling me, and return to the daily routine at a higher rate of effort to 'catch up': one strand of life gone awry poisons the other and it is hard to prevent it from doing so.
The idea of thinking something like 'I'd better hurry up with this home invasion and cut back on the usual masturbation because Deidre's invited her friends over for a barbecue at seven,' is utterly implausible, yet some of these mentally ill criminals, like Williams, sustain such existences--lives in which enormity abuts mundanity--for years.