Life Hacks/Charity,Billy(girl-like-relate),rape-girl-preg/Chrty pick + (kinder)78 pick/Mother4/Billy-friend/Table/Clean her up
Well, whether her size is working against you or not, it's better than your other options. First thing's first then. You've gotta get the large volume of cum out of her vagina. You don't have any kind of wipes, so you're going to wind up having to use toilet paper for this most likely. However, there's absolutely no way in hell the cheap single-ply toilet paper they use in restrooms like these will absorb this much fluid.
You look back to Billy's discarded clothing on the floor. That... may actually be your best bet. You walk over and grab her underwear out from her shorts, only to see that almost every inch of them with the exception of maybe a small patch in the back is completely coated in a film of your slime already. However, maybe if you wash these a little and get the cum out of them they would be good to serve the purpose of absorbing more of what's coming out of Billy's pussy right now.
You bring them over to the sink and, using your finger nails, actually scoop your thick jelly-like cum out from her underwear. If anything, having the liquid portion of the semen washed away and leaving only the cellular matter behind makes the semen even more sticky, and it's so incredibly thick that when you dump it in the sink it looks like someone put some spoiled curdled milk in the sink or something as the lumpy clumped together sperm cells stick to each other as well as the side of the sink.
You are also still left with a fair bit of the stringy stuff clinging to her panties, but you do not need to get it perfect. After all, you are only going to be messing them up again in a moment. You go back to Billy, still unconscious and sleeping on the changing table. She looks like she's just been completely used and abused and is a rather sorry sight. Her face is still quite red and her hair is all disheveled, her hoodie sweater is wet in back from your semen that had previously run down her ass the first time you fucked her, and it's being joined by more as it flows out of her and pools in the indentation of the changing table, and then of course there is the fact that she's naked from the waist down and your semen is still pouring out of her. She's a total mess.
You approach her and lift up one of the legs that's curled into the fetal position, exposing her groin to you, and then you reach in with the underwear. You made sure to use warm water while you were washing them so it wouldn't be too cold for this step. You press the warm and wet garment to her crotch and use it like a rag as you wipe the surface of her vulva clean. You then wad up a portion of the crotch of the panties and press them inside her vagina and start sliding them in and out of her, trying to swab out whatever fluids will come out this way, and then you pull them back out again. This leaves her leaking at a considerably slower pace and the panties sticky like they are covered in snot, but she is still leaking none the less. Finally, you give a quick wipe of her butt cheeks which have had quite a bit of your stuff running down into them before you take the garment back to rinse again.
You return with the underwear as your rag once again and begin using the freshly warmed fabric to attempt to get as much more of the stuff out of her as you can. She also sleeps through the whole thing, not even stirring as you wash her like this. Although, most of this could likely be chalked up to your delicate technique throughout. You maxed out your skills in everything, so of course being a master of washing someone's privates while they sleep without disturbing them is on the list. Such a specific skill, and you clearly have perfected it despite this being the first time you have ever done such a thing. Also, with the source of the mess being on her crotch, it really does seem like changing a baby's diaper in some sense.
Eventually, the task is complete. After this, you go on to scrub down her back. You would probably just make things worse running her shirt under water, so instead you scrub the insides of her shirt with your"rag" once again, reaching your hand behind her back and scrubbing your stuff off the inside of her shirt. You can't do the same with the shorts, there is clearly way too much of your sploodge all over the legs of them for that. You wind up running them under water in the sink and giving them the same treatment as the underwear.
There really is no way you are going to dry these in a reasonable amount of time, so instead you decide to just put her shorts and underwear back on now while the warm water will make it less of a shock for her to have these put on her. Now then, with that fully done...