Keep going

I look down at my step-mom's big tits while rubbing my cock through my shorts with one hand, and my little head rather than my big head does my thinking for me so I use my other hand to gently squeeze one of Millie's breasts.

I reach into my pants to get a better grip on my cock, and start jerking myself off. Slowly at first, but then I start picking up the pace. My shorts are getting in the way, so I push them down a bit to give me an unhindered range of motion for my jerking efforts.

Then, suddenly, Millie stirs a bit, so I spring back and just stand there and watch her, but after a few seconds I feel confident that she is still sleeping. My hand reaches out for one of her breasts, and then as slowly and as gently as I am able to I push her bikini to the side, revealing one of her naked breasts. I just stand over her, looking at her, then I push her bikini off the other breast as well, looking down at both of my step-mom's big tits.

For a while I just stand there, slowly jerking off while watching Millie, and then I lean down and kiss first one of her nipples, then the other one, while jerking my cock. I then straighten my back, and begin to jerk myself off at a furious pace while looking looking down at Millie's breasts. I feel that I am very close to cuming, and then, as I cum, I see my first wad of cum land on one of Millie's breasts, and the second wad of cum hits her in the face, and right after this has landed Millie opens her eyes, just looking at me neutrally, then with a look of horror as she sees the cum shooting out of my cock landing on her body.

Millie just stares at me in shock, and I am probably looking even more horrified as the realisation that I have just jerked off on my step-mom hits me, so several awkward seconds pass with us just staring at each other. Then, I feel I need to say something.