Does one pull out or drain your fertile nut deep

Alright...so You could not resist the urge to see your stage-sis bare. It starts off as playful sexual pressure, but then as her garments start to occur off... it gets really serious! Your brain is telling you this isn't suitable, but your interior primal instincts is not going to stop her as she starts to stroke here your challenging cock. Prior to deciding to know it, she opens her mouth, and you're feeling her tongue all over your idea... then her legs distribute as she guides your throbbing meat into her swollen wet vagina. It’s all happening so quickly; you’re pounding her as she moans!! Your balls swell up with cum, therefore you listen to your move-sis say...cum inside me! Do you pull out or drain your fertile nut deep inside her?