Couldn’t resist my nieces friend

Background: I'm a 35m, I live in a nice 3 bed apartment in the city centre and until 6 months ago I shared with my ex of 7 years.

My niece has recently turned 18 and has been going out a ton as expected. Often to late night raves etc and my sister is always worried about her getting home or staying somewhere safe etc. A couple of weeks back she mentioned her and her friend (I'll call her Lucy) had a rave on a Friday night and were looking at booking a hotel but as there were lots of events on the prices were really expensive. as I have a spare room I said if it's just her and her 1 friend and they keep it clean they can stay over and use my apartment.

Fast forward to the day, I was out and about and offered to pick them up, I'd never met Lucy before but as soon as picked them up I could see she was extremely attractive, 5ft little blonde and exactly the type of girl I would've gone for when I was younger. Obviously there was nothing untoward as I'm almost double there age now so I introduced myself and they hoped in the car to my apartment. On the drive and when I took them up Lucy was extremely nice and complemented my car, apartment etc and even my body. The last one being out of earshot of my niece but I just laughed it off and took it as innocent.

Later that night they came in around 2am and went into the bedroom, after a while it sounded like they'd gone quiet so I assumed they'd gone to sleep. I popped into my living room to get a drink, as I heard the living room door open behind me, I assume it was my niece, but it was Lucy… she asked if she could also have a bottle of water and we made a little chit chat. She said she always has trouble sleeping and is a bit of a night owl, I said I do too and often have a joint to help me sleep and was just about to roll one, she hinted that would be amazing and I said if she wants she's welcome for a few puffs.

I smoke out of the window in my bedroom as it opens completely outward and generally keeps the rest of the apartment from stinking. So she comes in, closes the door and sits on the bed and we're chatting and she's smoking with me.

Now, I'm doing my best to keep composed and not stare at her, her outfit was all white, a tennis skirt and basically a bra top with white Nike socks, it was extremely hot and she looked really cute.

She made several flirty comments about my body as I'm stood in my comfy night clothes (sport shorts and a vest) so I'm a bit on show. And then she makes comments about how I bet I have so many girls here etc. I laughed it off and said actually not for many months now since my relationship ended. But hinted I'm getting a bit pent up of being alone so will probably start dating at some point.

As this conversation progresses my guilt is kicking in and I know we're now flirting, alone in my bedroom and I'm beginning to feel horny and need to get this girl out of my room before my niece wakes up and wonders why the hell she's in my room.

Suddenly she slides back on my bed so her back is against the headboard and she's facing me (I'm stood up smoking towards the window and she plants her legs with a gap and I can see her bright pink thong through the gap.

I immediately felt blood rushing into my cock and as I just had sport shorts on and no boxers I could feel my bulge was beginning to show and I needed to get her out.

She was grinning while talking to me and kept staring down at my shorts, she knew I could see her pink thong and up her skirt. She adjusted 'innocently' so her legs were more open and I can see everything clearly. Right as I'm about to tell her I need to sleep now to stop this, she makes a comment about my bulge and says not just big muscles then but big everywhere, is that just from talking to me? You must be pent up.

For some reason her saying this sent me crazy and I began to get hard. so I quickly sat on the edge of the bed to try and mask it and she moved her foot so it was touching my leg. My dick was rock hard and poking like a tent.

There was suddenly unbelievable tension in the air and I felt like a magnet towards her I told her I can't help it when she looks like that and is sat on my bed with her panties showing. She said she could help me if I needed… I told her we can't do this that she's my nieces friend and im almost double her age. She moved her foot again so it was now on my shorts and her toes touched my cock in her little Nike socks. I was throbbing so hard and the tension was unbearable.

She said she promised she would never tell anyone, and it would ruin there friendship if she did and she swore it'll never leave the room.

That was it, we went for each other and started making out. I slid my hand up her skirt and her pussy was already soaking wet. I pulled her thong to the side and started rubbing her clit as we made out and she whimpered and grabbed my cock and starting stroking me.

I lost all control and pinned her down and slid to her pussy and began eating it, she was quivering in pleasure after a few minutes and i pinned her legs back and got on top, i slid my cock in but even though she was soaking wet, it was so fucking tight.

I could barely get a deep stroke in and within a few minutes she had her pink acrylics digging into me and her eyes were rolling back in pleasure. It was too much and I couldn't stop myself. I came so hard inside her and we both continued making out and holding each other. It was one of the hottest sex experiences of my life.

I told her how tight and amazing it felt and she admitted she'd never had unprotected sex before or been creampied and it was the best thing she'd felt. This turned me on even more. Reality kicked in and I said she should go back before my niece wakes up and we get caught.

She left her pink silk thong on my bed and said I can keep it to help me when I get horny and went to bed. I felt incredibly guilty and that I would be found out and get shit from everyone for this but it was honestly so hot and intense.

They left the next day, she added me on Instagram and message me innocently to say thanks for the hospitality. They had another upcoming event at the end of the month and I said they're welcome to stay again. They did, and once again I couldn't help it. If people are interested I can share what happened the next time