Fucking my step-mom in the ass

Millie hands me the tube of KY, then strips out of her clothes and gets into the doggy style position on the sofa. I also strip out of my clothes, and am standing behind her starting to put KY on her asshole.

Millie looks over her shoulder and asks: "You've fucked someone in the ass before, right?"

"No I have not." I reply, deciding not to exaggerate my sexual experience.

"Ok, let me guide then." Millie says.

"Put a bit more lube on my ass and use one finger to push it in." She says, and I do as she says.

"Ok, that is enough lube, now gently push one finger in to start opening me up." Millie continues. I slide a finger slowly into Millie's ass, and it feels very tight, I cannot wait to get my dick in there, I think to myself.

I can feel that my finger is now sliding easier into Millie's ass, and she says: "Ok, now slide a second finger in, and put more lube also." I put a bit more KY on Millie's ass, then gently slide two fingers into her ass. It feels tight, but her sphincter soon opens up so my two fingers are sliding in and out with ease into her ass.

"Should I put a third finger in?" I ask Millie.

"No, try to push your dick into my ass instead, but remember to push, don't thrust." Millie replies.

I take a bit of KY and apply it to my dick, then start pushing it against Millie's ass. Millie reaches between her legs with her hand and grabs my dick, slightly adjusting the angle so it is pointing right at her ass. I slowly increase how hard I am pushing, and then I feel Millie's ass open up and the crown of my dick slides in.

Millie let's out a groan, and her face has grown red, she is struggling to adjust to a dick entering her ass I can tell. I hold still for a while, then Millie says: "Ok, push it in all the way now." I slowly slide my dick all the way to the hilt into Millie's ass.

It feels amazingly pleasurable to have my dick in Millie's ass, so I start slowly sliding it in and out of Millie's ass while she lets out little yelps of pain each time I push into her ass.

"Oh my, your dick is too fucking big!" Millie moans with pain, her ass is clearly being stretched to the limit.

I don't respond, but instead slide my dick almost all the way out of her ass, then I quickly push it back in again, and Millie clenches her hands into fists, and screams "No!" I do it again, and when my dick has gone all the way to the bottom of her ass Millie screams "No!" again.

I am getting close to cuming now, so I scream:

"Your ass feels so fucking good Millie!"

"No!" Millie screams as I push my dick into her ass again.

"I love fucking you in the ass Millie!"

"No!"

"I am going to cum in your ass Millie!" I shout.

"Please cum!" She yelps, and I start pumping my cum into Millie's ass, groaning loudly in pleasure.