@messolini9 there’s only him and his mother. I really really doubt she’s strangling him with lamp cords.
You say she is in the process of divorcing the father, so presumably he had some presence in his son's life over the past 4 years. Maybe this father is the role model - it's not unusual for abused women to keep quiet about it, is it?
Maybe the son has developmental issues. Until you have a proper discussion with your friend about it all, you are never going to know.
Frankly, if she is divorcing & all alone with just her son, there is even more reason to urge her to engage with professional advice.
She either needs parenting help, or her child is acting out DV or television he has witnessed, or he has some form of special needs. Whichever one it is, your friend needs help wih him, & the best thing you could do for her is help her realise that & find it.
However, sad as it is, I don't think you will do that, because you are obviously more intent in sparing yourself from what you perceive as "confrontation" than actually knuckling down to help your friend:
or I could just plausibly disappear from their lives and spare her feelings that way as opposed to confronting her now
How on earth is that going to "spare her feelings"?
You'd rather disappear than give her the courtesy of truth & the helping hand of genuine support?
Here's a hint - REAL friends challenge each other. Real friends tell each other the truth. Real friends are there through difficult times, dealing with difficult & embarrassing emotion.
By all means, you absolutely must put your DD first.
Why you seem unable to do that while kindly letting your friend know that you want to keep enjoying her company but will no longer allow unsupervised play, is beyind me.
This could have been the springboard you used to launch your friend into accepting that she has a real problem with her son, with you supporting her as she accessed expert help for him.
Instead of that, you talk up a storm on here about "a tendency to over-react to threats" but in fact all you are prepared to do is scuttle away from the situation & hope that ignoring it, & avoiding your friend, will eventually make it, & your friend, disappear.
Why not choose to be a proper friend, allow your DD to play with this little boy you say she "adores", insist on supervision, be there for your friend as she goes through her divorce, & support her in finding the proper help she needs for her son?
You seem to be viewing any truth-telling as a "confrontation" that will "upset" your friend. It absolutely does not need to be - but of course only you can weigh up which is more valuable to you - your friendship, or avoiding witnessing the friend being "upset".