Let her prove herself.

"I don't know, Kayla...It's a tough situation." While you talk, you casually undo your belt. "What can you do to earn back the trust that you've lost with this indiscretion?"
She knows the score. She slips off her sandals, removes her bracelets and earrings, and places them on the desk, with no hesitation.
"Whatever you want...whatever you want...." she's repeating it like a mantra. "You can have anything. You want my pussy? It's yours. You want to fuck my ass? You can. I'll be your little pornstar, just..." she kneels down to pull open your shorts, and rubs your stiffening cock through your boxers. "...just tell me."
"Start sucking, and we'll see how it goes." If she was willing to give you every inch of her, then perhaps she was chastened enough that she could be trusted. But you're going to test that to its limit. If she balks, then she's out.
As she begins to spit and suck on your cock, you stroke her hair. "Oh, Kayla. What am I going to do with you?" She increases her pace, until you grab her hair. "This ain't a sprint, sweetheart. You're going to be occupied for some time." She slows down, paying better attention to every little contour of your cock, now.
"This is such an....ahhhh..unfortunate situation we find ourselves in, sweetcheeks. I won't lie, ever since that day, five years ago, when I walked into this office and found your riding my own dad on that couch, I've had a little fantasy of breaking you in. You've always been willful and feisty. I love that about you. I imagine you're pretty wild in the sack." She manages to smile around your cock.

You let her continue for a little while, and then you stop her, standing up, and bringing her with you. "I'm going to go sit on the couch. Your gonna strip down to your bra and panties, slowly, and then come ride my cock."
"Yes sir."
As you sit and watch, she slowly, sensually, peels off her sweater, swiveling her hips as she does it, and bending at the waist so her skirt rides up and flashes her thong. Her thick thighs are creamy and beautiful, and her ass jiigles pleasingly as she sways towards you, unzipping her skirt and slowly shimmying it down to her knees. She turns once more to show you her backside, bending double and blowing you a kiss from between her legs. Your jaw drops as she lets the skirt fall to her ankles, kicking it into the air in your direction. You catch it, and lay it on the floor, stroking your cock as she drops into a crouch, swinging her hair around her head to fall behind her. She then crawls towards you on all fours, slowly.
"Why Kayla, I never knew you had stripper moves. Have you ever worked the pole?"
She climbs onto your lap, pulling her panties to one side and exposing her snatch. "In college."
"Well, you haven't lost it, baby." You line up your cock with her inviting snatch, and you tease the entrance as you reach up to pop the enclosure on Kayla's bra.
As you slowly allow her to slide down onto your cock, she gasps, pulling your head to her chest. You suckle on one of her fake tits, and with one hand, you reach around and finger her tight asshole.
"Oh...James... we.....we should have done this a long time ago." Either she's sincere, or she's putting on a very good show.You don't care either way.
You work the finger into her asshole up to the second knuckle as she bounces on your cock, slowly, taking your instruction from earlier about not going too fast.
"Maybe you wouldn't be in so much trouble then?"
"Not if I had your hard cock to keep me on the straight...and....narrow..." she punctuates every word with a twerking motion, rocking back and forth on your dick. "Ahhhhh.....fuck. That's a nice cock...It's been too long..."
"Can't be trusted without regular fucking, huh?"
"Uhn-uh..." she shakes her head, and explores your mouth with her tongue. "I haven't been properly fucked in two years, James. Thank you for fixing that."
"Get off. Your mouth is doing too much talking. It needs something to occupy it." She hops off of your throbbing cock, popping it into her hot mouth, still slick with her own pussy. You peel down her panties with your free hand, while you apply pressure to the back of her head with the other. "All the way down, sweetheart. You can do it. I believe in you."
She chokes and splutters, but gets to the bottom. Her throat is amazing, and she's swallowing the tip of your cock, which feels incredible. You plunge two fingers into her asshole, which is spasming and pulsing. She gives a gurgling cry of pleasure and pain against the dick lodged in her throat, and she starts sucking all the way up and then all the way down your cock in long, fast strokes, leaving a film of slippery gag spit all over your cock. She knows where this cock is going, and she's trying to lube it up as much as possible.
"Time to take this thick cock in that ass, Kayla. You want out yet? Say the word, and you can hit that door."
She falls back against the arm of the couch, panting and drooling, her eyes bulging and tears running. "No..."
"No? You don't want my dick in your ass? You want to leave and never come back?"
"No...I want to stay."
"What's going to happen if you stay?"
"You're....you're going to fuck my ass with that big thick dick." her eyes are wild.
"So...what do you want?"
She looks at you and you can see any scrap of defiance die in her eyes.
"I want you to fuck my thieving, dishonest, faithless asshole, James!" she's rubbing her pussy now, and flips over to hang off the end of the couch.
"Well, since you asked so nicely..." you sit up, and start working your tip into her little rosebud, until you manage to push past the resistance.
"Ahhhhhhhhhhnnnnnnnnnn......!" She's really moaning now, pleasure and pain mixed together.
You keep sliding, inch by inch, until you can't get any deeper.
"HOLY....FUCK! That's sooooo fullll...." she's gone. Kayla has bluescreened. Her jaw has gone slack and she's letting out a low wail.
You pound that ass, reaming her tight hole to the music of her ecstatic babbling.
"Ohmy..Ohmygod..Ohfuck.....pleasepleaseplease.....yes.....ow....fuckfuckfuck...." your balls are slapping against her cunt as you lift one of her legs to get a better angle. The change in tightness sends you into the stratosphere.
"Kayla...I'm going to cum!"
"Cum for me, sir! I'm yours. Use me!!!!" You pull out, holding the tip of your dick to ride the edge. With your free hand, you flip her over, and dump a huge load on her chest, tits and stomach....
"Wow....so....much...." she's panting.
"Very good work, Kayla. I think we can come to an understanding after all. I won't be calling the cops, and you get to keep your job for today." She smiles, pure relief on her face. "But there's still the matter of your debt. It needs to be repaid one way or another." The smile slides from her face.
"Oh...."
"yeah..." You take a moment to rub your cum all over her tits, chest and stomach until it's evenly coating her skin. "Wear my cum for the rest of the day. To remind you that you belong to me now."
".....yes, sir." she's sniffling a little now.
"Don't worry. This was a little rougher than I intend to be going forward, because it was a punishment. That's done with now. Now, it's about paying your debt."
She nods, slowly. "O......ok...."
You lean down to give her a kiss, with tongue swirling and biting her lip gently. "Come over for dinner tonight when your done. 4:00 PM. Dress for a pool party....but don't wash my cum off. If you get to my house, and you don't have my cum on you...."
She nods quickly. "I understand."
"Good."
Kayla ducks into the bathroom to dress, and fix her makeup. You sit for a minute, reveling in the decadent power play you just pulled off.

You return home, cursing the amount of time you've wasted at the office as you hit an unexpected traffic jam. You're going to be late getting home, now. Jenna's gonna be hella pissed. Even worse, you realize that you didn't gas up, so you spend another twenty minutes trying to maneuver your way into a busy gas station. By the time all is said and done, you pull into your driveway to the sight of everyone on the lawn, hugging and greeting each other. God fucking damn it. You had wanted to be home when they got here.