Sorry for the long rant, but had to get it off my chest

My sister in law can be pretty childish, but I've always just kinda chalked it up to her quirky personality. We used to be really close. In recent years shes gotten to the point where I try not to even be in the same room. I dont exactly avoid her. I just try to limit my time around here. It all started when I got engaged. She got mad that I was engaged even though her and my brother had been together for a year longer. She told my brother to go out and buy her a ring a month later. My brother had a huge proposal ready, but instead when he got home she took the ring out of his pocket and decided that meant they were engaged. He was so upset he didn't get to propose the way he wanted, but he was just happy she said yes. She then proceeded to ask me when I set my date for so and I quote "I can get married before you. We have to get married first because we were together first." I tried to just brush it off. A month before her wedding she tells me shes thinking about leaving my brother for a guy that had been flirting with her at work. But she said since the wedding was already paid for that she had to go through with it and that she really didn't wanna waste the honey moon. They've been married for a little over a year now and my brother waits on her hand and foot. He works 5 days a week at a moving company he recently became in charge of. She chose not to have a job because he makes enough money. No biggie. Except that she refuses to eat unless he cooks or they eat out and she refuses to clean. Then I found I was pregnant. A few months later shes pregnant. I took her out to lunch to celebrate. My brother is such a nurturing guy. Hes ecstatic about this baby. She proceeded to tell me that she wants an abortion, but since she already posted on Facebook that she was pregnant now she has to have the baby. She even said that she wouldn't be upset if she miscarried, but that she loves the attention shes been getting. Every time they get into an argument she brings up abortion and it breaks his heart. Shes been telling him she cant clean or even do laundry because shes pregnant. He had to hire a maid because he works 60+ hours a week and doesn't have time to do it himself. She told me she was going to plan my baby shower, but then 2 weeks before hand told me never mind because shes pregnant. She was only 6 weeks at the time and had said she was planning it for 2 months. Im so worried for what my brother is going to go through once this baby gets here. His wife still acts like shes 18 half the time. All she wants to do is get dressed up to go to the mall.