Accident

So before our parents got a home security system, I would sometimes sneak out of the house and meet up with friends. As well, my one year older sister who just got out of high school also did the same thing till she got caught. I talked to a 20 year old guy here there who is brothers with my high school friend. She seemed pretty cool most of the time. I know at one point my older sister had a huge crush on him before he left high school and had to get a job. Then when my sister said she was going to meet up with friends here and there sometime couple days a week she seemed to be lying, which I asked her a few times if she was seeing a guy? Then one night she came home giggling, saying she finally hooked up with one of her crashes which she had a few so I was a bit confused.A week older the older guy started messaging me on Snapchat and he might just have a crush on me. After a couple months of messaging back-and-forth, I did at one point send him a little teasing pic pretending I didn't mean to. It was me trying on sexy fishnet leather top lingerie thing. This seem to really get his attention and he message me more and more pretty much daily now. Even was when I was in classes he seemed to not wanna leave me alone. Then out of the blue one day, he sent me a pic of himself hard on his lunch break at work. Not gonna live never had a guy do this before and it made me feel kind of special, so I sent a pic of me bending over and showing a little bit of cleavage with my shirt on.Finally, I told him one day to come pick me up in the dark so that my mom's camera would not catch me, anti-surprised he did wait for me at the road from my house. At this point in time I had already had sex with a few guys but nothing special or good. Yes, I'm young and I probably shouldn't have but figured I'd try it before I get older when I got into his truck it didn't take long and he already had his hand up my shirt in his big jacked up truck and wanting to kiss. But I chose to pretty much skip the kissing part and just setback letting him do his thing, which went from feeling me up top right away rubbing me through my jeans to my crotch. I really didn't think this older guy would've even showed up so I wanted to make sure that he felt special as well I wanted to feel the same. So I told him to takeoff his sweatpants and just sit there, which he did, and I took off my jeans. Then I climbed on top of him sliding my thong to the side and hovered above him, making his tip go back-and-forth on my slit. I got a little wet and sat on him fully.I was quite surprised when I just did my own thing going up and down on him, making sure I made a good impression that I was good sexually enough for him. Never quite rolled a guy like this before, but I thought I did what he would just like. I don't think he even lasted five minutes and I made him come. We got dressed and sat there for a few minutes on the side of the road and he mentioned how sexy and open I was to him. Not to mention.He said my pussy was the Titus. He's never felt. We continue to do this throughout the week, maybe 2 to 3 times a week for about a month. Then I got caught trying to sneak out from my mom, as well. My sister did too whoever she was seeing at the same time. A week went fine. I hadn't heard anything from him. Tell my mom had mentioned that my sister had a boy sneak over and she saw the guy come to the house on the security camera. Like was this her friends with benefits? A couple mornings later everyone was gone and I was having a bowl of cereal when I realize my mom forgot her phone at home. I heard a few things go off, and I saw that she had alerts from security camera. Her phone never had a passcode.So not gonna lie I started to snoop and play back all the footage of the security cameras. What I came to realize was the older guy that I had been seen came over when my sister was home and this was the guy that got caught visiting my sister? Like what the hell? My sister came home on her lunch break from work and I had asked if she had been dating or seen a guy lately and she admitted that she was trying to date my young friends, older brother. Which happened to be the guy I had seen a few times and let in my pants. Then I asked further questions to see if they were a sexual thing which my sister said yes unfortunately, so much that my sister really wanted to date him. Apparently they have been seen each other for a while to the point where she wanted to take it a bit more serious and not let him wear condoms anymore. So basically what I realized was.That guy was having sex with both of us without us knowing about it. I really didn't want to hurt my sister in her knowing that he was a douche bag, but I'd have to tell her eventually what him and I had done! It's been about a week and I refuse to respond to his Snapchat for respect for my sister and will be telling her soon about him being a piece of crap possible future boyfriend. The crappy part is that I miss him