Cum while she's standing there

Even with the shock and embarrassment of having my sister-in-law walk in on me while masturbating, I can't stop the cum from building in my balls. Knowing the inevitable that is about to happen I can't do anything except stare at Samantha's wide-eyed face while the cum travels up the length of my shaft. She is staring with rapt attention at my cock, I can't tell if she's mortified, excited or just stunned, maybe all three. My shaft jerks as the first stream of cum shoots out of my cock. As this happens Samantha's eye's grow wider and I see her chest rise and she gasps and takes in a breath of air. I can't help but grunt and close my eyes as the orgasm washes over me and my cock continues to jerk and spurt out my remaining cum.

After the moment passes I open my eyes and see Samantha turning around and walking back out into the hallway. I don't know what to make of this incident, I may be in trouble, I will be in trouble if she talks to her sister.