Passionate Cheating Affair

Years ago you moved to the UK for a couple of semesters, and while you were there you stayed with a host family. Now the step-daughter of that host family, Fiona, has moved over to the States for a job, and you and your wife have offered to let her stay with you for a few weeks until she finds her own place! As she's moving all her stuff in you introduce her to your wife Kate, and the three of you chat a bit about how you know each other, and how you used to live with Fiona in the UK. Over the next few weeks you and Fiona grow gradually closer, with Kate often working late or being out of the house, and the two of you finding yourselves alone together a lot... The tension slowly grows until one day, after Fiona has found an apartment and is preparing to move out, she shyly and guiltily confesses her feelings to you. She tells you that she knows that you're married, and that Kate has been so nice to let her stay here, but she just can't help how she feels... You assure her that you feel the same, and that you've been trying to fight it, but you don't think you can any longer! The two of you begin making out, then Fiona begins stroking your hard cock, and just as you're pulling Fiona's top up you both hear the front door opening, and realise that Kate's arriving home! You both spring apart and promise to talk again later, and you go downstairs to greet your wife. A couple of weeks later, Fiona has now moved into her own apartment, and you go visit her. The two of you sit on the bed and talk about how much you've missed each other, and how guilty you feel misleading Kate like this. Fiona asks if you're sure you want to go down this route, as she doesn't want to pressure you into anything... You reassure her that you want this just as much as she does, and the two of you begin passionately kissing. Fiona strips out of her clothes, telling you that you should both just try and forget about Kate for the evening, and just focus on each other. You begin eating Fiona's pussy, making her moan and squrim, but she can't seem to stop herself from fretting about Kate every now and then, and telling you how bad she feels about cheating with you like this! You pleasure her with your tongue until she begs to feel your cock inside her, so you get up on the bed and slowly enter her as she looks up at you. You fuck her slowly at first, then begin pounding her hard and fast until she cums. She then begs to suck your cock, and she worships it with her hands and tongue as she tells you how good you taste and how badly she's been wanting to do this. She tells you she needs your cock back in her pussy, and asks you to pound her from behind - so you flip her round and begin fucking her passionately in doggystyle, until the two of you cum together explosively! Afterwards, the two of you are laying on the bed together, kissing and cuddling, and you begin to get hard again. Fiona strokes your cock until you're completely rock hard again, then tells you she wants to ride you this time. She gets up on top of you and begins slowly and sensually riding and grinding on your cock, gathering speed until she cums hard! Then she slows down and focuses on you, whispering and begging for you to cum in her once more, as she moves her hips sensually. You fill her with cum again, then you get a text from your wife asking where you are! Fiona sadly kisses you goodbye and promises to see you soon, saying that she's so excited for your future together...