My Older Sister Is Pregnant And It Could Be Mine

Our mutual attraction became irresistible, and we gave in on my birthday, as soon as it was allowed.

She also has a boyfriend. I find him annoying and it makes me jealous when she is intimate with him.

I figure I get her like one quarter of the time and he gets her like three quarters. Obviously he doesn't know about me.

There's a good chance her baby is mine, based on when she met each of us. I really want to get her BF out of the way, start a committed relationship with her, and raise our child right.