Word for explaining something cruelly

Solution 1:

"You'll be the scapegoat for this and there's nothing you can do about it," the villain jeered.

jeer (v.)

To speak or cry out with derision or mockery m-w

Make rude and mocking remarks, typically in a loud voice. Lexico

He let Barry go with a threat “Tell anyone and I'll come to your room one night,” he jeered into the boy's face, “and kill you! R. J. King; Sylvia Rose

When he dismissed everyone else, he jeered in my face, "I'm going to run you down. I'll make you hang or shoot yourself just like the other soldiers who crossed me." J. Bardach and K. Glesson; Man is Wolf to Man: Surviving the Gulag

Solution 2:

One of the verbs nowadays accepted as expressive quotative verbs is gloat.

Private First Class Bradley Manning may have done a first-class disservice to US international relations, but by allegedly copying classified files on to a CD, he has changed not just the course of history, but how it will be written.

“I listened and lip-synched to Lady Gaga’s Telephone while ‘exfiltrating’ possibly the largest data spillage in American history,” he gloated after this feast of raw, contemporary history was pitched into the public domain. Centuries hence, historians will still be citing the Manning hoard.

[Ben MacIntyre; The Times; Nov 30 2010]

"This is called the old game of keeping the headmaster in," he gloated.

[Peter Symonds College]

This is an extended usage, the prototypical intransitive verb, obviously with closely related meaning, being defined:

gloat [verb] [no object]:

Dwell on ... another's misfortune with smugness or malignant pleasure.

[Lexico]

Kate Bunting suggests another equally acceptable modern quotative verb (sneer).

Visser describes this phenomenon (and a further development):

Transitivisation [of verbs] may also have been furthered by the fashion which set in in later modern English – especially in novels – of treating verbs expressing human and animal sounds (such as bellow, coo and groan) as well as verbs such as smirk, smile and persist as if they were synonyms of say by giving them the quoted words as object [ie using novel quotative verbs]. From

She smiled “I don’t believe you”

and

He grunted “I thank you”

to

She smiled disbelief

and

He grunted his gratitude

was only a step.