Slutty Niece

I have a niece Sydney (not by blood) she is a 18 a little slutty and very much a tease to boys and men. She is flirty and sometimes over the line touchy. While visiting or family dinners she would look at me in a way which i knew was not good. She would walk by me when know one is looking and stick her ass out and grind it on my dick saying whoops biting her lip. She walked in only on purpose when changing to get into the hot tub just to get a look of my cock. she was stealthy at it never really getting caught...until one day.
About a month ago while her mom was away i was checking on the house every couple of day, like checking mail, the hot tub, water her garden and all was good. The one Saturday i go ever around noonish, no cars still so i obviously let myself in check out the house about to leave when i look out the back window to the hot tub and i see clothes and towels on the deck, as I'm about to go outside there are 3 guys standing there naked and i, about to lose my shit when Sydney hops out of the hot tub naked and is walking over to them i hear her say (no sex just sucking) and starts kneeling down in front of them and starts to suck there cocks. I am shocked but at the same time i can't turn away. I grab my phone and start recording. She started with one dick taking turns but then turned into her stroking 2 and sucking one swapping all over back and forth, it looked messy but the guys were loving it and Sydney looked to be having a lot of fun, this went on for about 10 minutes when she said to the guys (i want you to cum all over me) the 3 guys moved in a little closer and stood around her jerking off, the one dude started slapping his cock on her face and grabbed her head and stuck his whole ball sack in her mouth, shortly after that the dude say there are ready,Sydney says me too, and just like that these guys are shooting cum all over her face and tits shot after shot, its everywhere, eyes,hair,ears, shoulders tits running down to her pussy. That saying young dumb and full of cum, was what i was witnessing. blinded and cum covered she sucked there cocks and cleaned them up, the boys gave her a towel and all went back into the hot tub and i got the fuck out of there. quietly in quietly out. i would be lying if i didn't say i went home after jerked off because hell yeah i did. Just recently we had another family gathering at the end of summer at her moms place again and while all the adults were in the hot tub i asked Sydney to come inside and help me with dinner cleanup, as she came inside i was on my phone and she asked me what was i looking at? i replied I'm not sure you tell me and i showered her the video of her sucking those dicks, her face turned red instantly saying OH MY GOD and i told her to stop being so touchy and flirty or ill show your mom, she didn't even seem to care about me telling her mom, she said your probably just jealous and yes i guess a little bit but thats not the point, Sydney tells me (your saying if i said i would suck your cock you wouldn't want to blow all over me face? and i was like well i mean i shouldn't but you would right? so i admitted yes of course i would. Sydney says exactly and started rubbing my dick and i totally let her do what she wanted, she pulled my swim shorts down and started sucking my cock right there in the kitchen she said why don't you record this too which i did, she sucked for a good 5 minutes before i took it out of her mouth and asked her to say it ( cum on my face) and she did and i exploded on that face rope after rope of jizz. i helped her to the bathroom for clean up and now we have an agreement to never mention any of this for the rest of our lives