Joffrey's Sadistic Treatment of Tommen (Spoiler's Extended)

We are given numerous examples in the series of Joffrey treating his younger brother terribly:

"Prince Tommen is hale and happy, my lord. He has adopted a fawn some of my men brought home from a hunt. He had one once before, he says, but Joffrey skinned her for a jerkin. He asks about his mother sometimes, and often begins letters to the Princess Myrcella, though he never seems to finish any. His brother, however, he does not seem to miss at all." -ACOK, Tyrion XI

Joffrey is also known to have cut open a cat to find the kittens as well.

The real point of this thread is this quote:

This will not do. Too many eager ears and watching eyes. "Best we go outside, Your Grace." Jaime led the boy out to where the air was as fresh and clean as King's Landing ever got. Twoscore gold cloaks had been posted around the plaza to guard the horses and the litters. He took the king off to the side, well away from everyone, and sat him down upon the marble steps. "I wasn't scared," the boy insisted. "The smell made me sick. Didn't it make you sick? How could you bear it, Uncle, ser?"

I have smelled my own hand rotting, when Vargo Hoat made me wear it for a pendant. "A man can bear most anything, if he must," Jaime told his son. I have smelled a man roasting, as King Aerys cooked him in his own armor. "The world is full of horrors, Tommen. You can fight them, or laugh at them, or look without seeing . . . go away inside."

Tommen considered that. "I . . . I used to go away inside sometimes," he confessed, "when Joffy . . ."

"Joffrey." Cersei stood over them, the wind whipping her skirts around her legs. "Your brother's name was Joffrey. He would never have shamed me so." -AFFC, Jaime I

I have always read this to mean that Joffrey abused/bullied Tommen, but I recently talked to someone who thinks Joffrey sexually abused Tommen (like Euron/Aeron).

For me the problem is that Joffrey has not shown any interest in sex (other than having Sansa stripped naked, and tormenting her). Tyrion even considers taking him to a brothel, thinking that it might change him.

What do you think?