Pull out!

"Oh shit!" you desperately stop your frantic pounding, planting your knees and pulling out just in time to paint Tara's creamy ass cheeks and arched back with your load. You grunt and groan as you pump, working her spasming pussy with two fingers as you do.
After squeezing out every drop, you collapse onto your back next to Tara. She's panting, and squirming with ecstasy on the top sheet, bathing in the warm afterglow of her orgasm. Her eyes find yours, and she props her face up on her hands.
"That was a close one, big boy." You are pleased to hear that she is breathless: you are in pretty good shape, but fucking a nubile 20 year old girl has pushed you to the limit.
"Next time..." shit...will there be a next time?! "...give me a little more warning, Tara. Why aren't you on the fucking pill? Are you trying to make me a grandfather?"
Tara leans closer, running fingers through your hair and rolling onto her side. You note, with some consternation, that your cum will now be sliding onto Jared's pillow. Tara either doesn't notice, or doesn't care. "I ran out. Jared and I have been using condoms for a week now." She giggles..."It felt so good, you pounding my little pussy so hard...I guess part of me wanted you to fill it up." She's grinning.
You aren't so pleased. "Tara..." you swallow hard. "...we can't...this was, I don't even know how this happened..."
"Oh you're so sweet, Mr. James." she leans over to peck you on the lips. "Don't worry. This was a lot of fun, but I'm not trying to wreck what you have. It was just...a little pressure release. I could tell you needed it. I definitely did. That cock. Mmmmmmmmmmmhmm! It's addicting, James! No wonder Jenna seems so happy all the time."
Jenna. You've gone and done it, cheated on the most beautiful, sexy and loving wife in the world. "Oh no..." you're starting to feel the guilt, the shame that you pushed away in service of your dick.
"Hey...James! No, please don't get upset! I'm not going to do anything to fuck your shit up. We can pretend this never happened. I had fun, and I know you did too!"
You aren't so sure about her plan to just go back to the way things were before, but what can you do except try?
"Okay, Tara."
You get up, wrapping your towel around you. Tara gets dressed in her acid washed cut-offs, knee high socks and Skechers, and pulls a black v-neck t-shirt over her sizable rack. She peels the pillowcase and sheets off Jared's bed. "I'll throw these in the washer. I have to go home by 2:00 to get ready for work tonight, but I can give you a hand with getting ready if you want!"
Huh. You guess turning Tara into a helpful young lady instead of a vexing little tease is a silver lining to this whole thing.
"Thanks, Tara."
"You're welcome." She passes by with the laundry, pausing to lift up on her toes and brush your lips with a kiss.

This...isn't over.

The rest of the morning is spent in tidying up and trying to shed the blanket of guilt that's plaguing you. Never before had you broken your wedding vows. Well...you had gotten a blowjob from a stripper at Dane's bachelor party, but that was it! It's not like you had fucked her!
You clean up the yard, check the chlorine in the pool and the jets in the tub, while Tara takes out the trash and finishes Jared's linens in the laundry. When Jenna returns from the store, Zoe trails her in her own beat up Malibu. They must have stopped off to get it. You all pitch in to help put away the bounty of groceries, and just as the last bit is in the pantry, you hear the twin honks of horns as they pull in the driveway.