Announcing to Family.. NEED HELP

My DH and I just found out we are pregnant with our rainbow baby. We miscarried our first 8/4 and are about 6 weeks pregnant with this pregnancy. My SIL miscarried as well on 7/13 and she has made it known that she will be pissed if I become pregnant before her. (Im 23 and she is 31). Well, we are announcing to our whole family tomorrow and I am nervous how she will react. Is there anything I should avoid saying or make sure I say? I don’t want to make her mad but I am super excited that we are expecting and don’t want to hold it in!!