I don't know how to tell them!

In January my family suffered the loss of my beautiful baby niece, my brother and sister-in-law's first child. She died during birth completely unexpectedly and my family has been grieving ever since. My sister-in-law is angry and broken and wants nothing to do with babies since losing hers. 
And now here I am, 7 weeks pregnant and I don't know how to share the news with my family, I love them so much and I don't want to hurt them. 
I've told my parents, I know it's a scary thought for them to open their hearts to another grandchild after having lost their first one in such a tragic way. They are taking it one day at a time, just like I am.
​I have absolutely no idea how to tell my brother and his wife. My own heart still feels broken after losing my niece, I can't begin to imagine how they as her parents feel.  
​I want to feel joy with my family again but I am afraid of the resentment that I may cause my brother and his wife to feel. At some point I know I will have to tell them, whether they react good or bad, I'm just reaching out to you all in hopes maybe someone has had a similar experience and can offer me some insight on how to respectfully share my happy news.   
​Anyone have thoughts?