Frustrated sister in law

So I found out I was pregnant about 3 days ago and the first person I wanted to tell was my sister in law who lives with us. She recently was pregnant but it turned out to be a blighted ovum. Now after 6 years of TTC I finally got a BFP. But she is upset that I am pregnant. She has 3 kids and a step son and my only child will be 11 this year. I could really use some help and some advice with this.