Sometimes you've just gotta have it, or him, or her, the character you dread to write because the person is such an idiot/bastard/unredeemable pustule of misogynist actions and motives that makes your skin crawl, your stomach roil, and your soul cringe.
Then the old chestnut--if there wasn't evil what would good do--pops its questionable tendrils out and you need to deal with that pile of used kitty litter.
Making a likable or interesting evil doer is easy, give them a 3D background, a well-rounded life, habits, quirks. Hannibal Lector is a fascinating example of this--an erudite, well-mannered gentleman of leisure who likes fava beans and a nice Chianti with his kidney, freshly taken from an unwilling donor. I can't abide tongue so I don't care whose organ meats are on the menu. Err on my part, I do like pate and liver with onion and bacon, so on with the show...
Premise: an evil woman uses mutilated children as beggars to bring in money from passersby. This is nothing new, still happens in the poorer countries with too many mouths to feed and too little money where your favorite sports shoe manufacturer pays 12 cents a day for the workers to spread toxic glue and sew up those $200 sneakers hawked by that multi-million dollar hoopster, but hey, everyone is entitled to make a buck.
If the child isn't fit to work or would do better as a prostitute, that's their strength. Even their own would pay more pennies to a begging child with stumps than one hale and whole. It's the ugly truth of the world.
I abhor child abuse, animal abuse, elder abuse. Which is done by all layers of educational/socio-economic areas.
What tells us of this unpleasant subject? That we retch thinking of doing it so it's easier not to write it? Are we doing it for shock value? See above, that's easily done. Are we doing it to show the evils the world can do, see above again. Is it to advance another character, one who must witness it or be a part of the chain of hellish events in order to move on to the next level?
How does the writer face that 'icky' part and get through it? Does writing about the evil make you the same? Does it anesthetize you to the proliferation of foul acts, or educate you? Do you face something inside that resonates and that you must overcome? Can you understand or rationalize the bad guy's actions? Does it serve the purpose in the scheme of that novel?
We're way beyond the 'you must know the subject' to write about it. No one needs to be a medieval trooper to use a crossbow. Research and finding references can do the job, little details like getting a splinter from the stock and your bunkmate likes to pick his teeth with a quarrel tip do more for authenticity than the exact measurements.
Face the demons, write through what makes you want to puke. Even if you never use it, it's a growth of your writerly soul. Nothing is wasted.