Family Ties/Gently discourage his actions.
You don't have to fake the shocked expression on your face at Timmy's request to see your tits. He has always been a chronic peak but up until now it was just some harmless fantasizing, what could easily be dismissed as childish curiosity. But his present request and the look of lust on his face tells you it's just the beginning of what he wants.
You glance into the family room, concerned if your husband had heard anything but with the volume of the T.V. that's seems very unlikely so you return your attention to your son, still darting his eyes back and forth between your face and your cleavage. "Baby...., We shouldn't. I mean I shouldn't." You manage to stammer out in a whisper. "Besides your father is right in the other room."
"He doesn't love you!" Timmy whispers in a harsh tone. "Not like I do." Timmy shakes his head and then motions out into the living room. "Look at him.., glued to the T.V. He doesn't deserve you."
You have a hard time coming up with any thing to argue your son's point. It's been a long times since you actually felt wanted by Steven. Certainly not to the point of being aroused, not as aroused as you are right now. "Baby..., I can't." Is all you can come up with.
Timmy's eyes hit the floor and in a very low whisper he says, "I'm sorry..., I just.... Sorry."
Damn it You think to yourself. I broke his heart. You stand there and ponder what to do. On one hand what could a little peak really hurt.
On the other hand your smart enough to know Timmy will likely not be able to stop himself once he sees them.