My Brat of a sister

My sister had always gotten everything she wanted, and our parents always gave in to her. I, on the other hand, was expected to do everything expected of me. I graduated college top of my class and started a great career. The family was financially okay till the day our parents died in a car accident. Then the house of cards came crashing down; the house was sold to pay off the debts, which also took the insurance payouts as well. My sister was still in college, and I had to pay her tuition fees. I had my own place, which I owned outright. I'm 5 years older than my sister, a nerd according to her. But now she needed me to support her; working to earn money wasn't something she had ever been asked to do. My social life was nonexistent, as I had always concentrated on my schooling, then my career. My sister wanted more than I was giving, was not willing to work to earn the extra money, and asking me wouldn't work as it did with our late parents. So, she decided to seduce me, hoping to get what she wanted. In a way, it worked; in another way, it backfired. The condom she used was old or faulty, as it broke inside her at the wrong moment. She got pregnant; with no abortions allowed in our state, she had our child. He was perfectly healthy, and my sister became very motherly. Stopped partying and dropped out of college to raise our son. Acts as my wife since we relocated to another house, selling my first home. Buying a new one, where the neighbors didn't know we were brother and sister. She sleeps with me every night and wants more children, which at first shocked me; I never thought she would ever settle down.