Stay and continue to jerk off.
From Create Your Own Story
As much as you would love to fuck your horny mother, who is probably still on the couch playing with her self thinking about you, you have to find out where this ends up going. For the first time since Heather started talking her face doesn't seem as angry as she had been. Out of no where Heather climbs onto the bed and straddles Jake, holding him down with the palm of her hand in the center of his chest.
"Don't fuckin' lie to me Jakey.., all you want to do is screw me so you can tell all your little 13 year old friends you fucked a slutty 16 year old. Just admit it Jakey." Heather tightens her grip on your brother with her thighs and grinds down hard on his crotch causing Jake to audibly moan. "I knew it, I can feel your raging hard on even through your shorts."
Jake pushes her up by the shoulder causing her to lean up, a slightly shocked look on her face. "Of course I have a boner right now! The woman I love is sitting on me naked!" He says to Heather while staring intently into her deep green eyes. You have to admit that despite the fact that your big sister's tits are literally inches from his mouth he is doing quite well at keeping his hands on the bed. "Every time I close my eyes I see you.., When I sleep I dream about you. Not just about fucking but running away together, having a family with you. To see you pregnant with our baby." Jake leans up slightly still staring into her eyes with his chin literally an inch for her hardened nipple. "Heather I am in love with you.... I need you." He whispers with a pleading look on his face.
After Jakey was done talking you weren't sure which way Heather was going to go but you didn't have to wait long for your answer. "Oh Jakey, I love you too!" Your sister cried out before grabbing Jake's face and cramming her lips against. Jake responded immediately by cramming his tongue into her mouth and wrapping his arms around her body. After a few moments of making out Heather broke the kiss and pulled back enough to yank Jake's shirt off. Then, after tossing it off the bed she grabbed the back of his head and pushed one of her taught nipples into his mouth, moaning loudly as Jake started to suck.
Jake spent a good 5 minutes squeezing and suck Heather's titties before grabbing her around the waist and rolling her onto her back and getting between her legs. "Heather I need you so bad!" He moaned while fighting to get his shorts and cock free.
"Oh God Jakey fuck me!" Heather moaned while hooking a foot into the waist band of Jake's boxers, forcing them down. She then shook her head. "I tried to be angry with you baby.., but I couldn't. Even on the computer you made me so fuckin' horny, I wanna feel that way all the time." Heather begged as Jake finally got his ridged 7 inch cock free and pointed at his sister's sopping wet cunny. "God I love you Jakey, I love you so much...., now fuck me!"
Looks like they are really going to do it. You could: