Sucking cock while he looks at my sisters nudes

So first of all I am a bi male, and I happen to have 2 extremely attractive sisters. Throughout the years I’ve been able to get ahold of their nudes and some videos of my little sister (25) sucking cock. For the first couple of years I just used them to jerk off to. Then one night a “straight” friend of mine that I give head to on the regular was coming over to get his dick sucked, and I like to suck his cock while he watches porn, and I remembered that he really wants to fuck my sisters. So when he got there I sit him down on the couch and pair my phone with the TV and hand it to him with the album of my sisters open and he can’t believe it, he’s thrilled to be seeing their bodies, and gets hard instantly before I even touch him. I start sucking his big juicy dick as he scrolls through the photos and he’s being much more vocal than usual and I’m loving it. When he gets to the first video I start to feel his cock twitch in my mouth and he starts cumming, normally I can blow him for up to an hour before he cums, this was the fastest he’s ever cummed for me, and I was going real slow taking my time savoring his taste, but it was no use he only lasted about a minute and a half while watching my beautiful sisters. And from that day on I’ve been sucking guys off to my sisters every chance I get, there are so many boys on Grindr that aren’t gay but just want a blowjob and they have all loved my girls.