Sister and I are pregnant together and she's upset about it

My sister and I haven't been very close since we were kids, my parents divorced and she lived with my dad while I lived with my mom. She found out in August she was pregnant with her first baby, I was super excited for her. Well in November I felt really weird and my period was 5 days late, I took a test and sure enough I'm pregnant also. I got married last Friday and my little sister accidentally spilt the beans about it and my sister's mood completely changed. She has been really bratty towards me lately, I try and talk to her and she has a huge attitude. I don't know why she's being so negative about this, this is supposed to be something exciting and special and it's honestly ruining my excitement. This is my first baby so I'm new to this and so is she, I was really excited when I found out since we get to go through this together and we could help each other. My husband is in the Army and we move in year, I will be far away from my family so I just want this last year around my sister to be happy. I don't know what to do anymore, any suggestions? I want to talk to her about it but I have bad anxiety and every time I plan to my anxiety gets in the way.