Advice on sharing my pregnancy news with my sister...
My sister tried to get pregnant for 10 years. She had an ectopic and had to have one of her tubes removed.
They did in vetro and it was successful. They now have a 3 year old girl.
They came to terms with this being their only child. They gave away all their baby stuff and have moved on from the dream of having more children.
A few weeks ago she found out she was pregnant! Total surprise, and medically basically a miracle due to her infertility.
Today she had an ultrasound and found out it was ectopic and is currenty waiting for surgery.
She hasn't told anyone, but my mom is with her and called me crying. Apparantly my sister is devastated and says she can't survive this.
The kicker is that I am pregnant. I have not told anyone, but I am about a week farther along than she is.
How in the world do I tell her that I am having a baby, and will be due about a week before she would have been. I can't do that to her...it seems so cruel for her to now have to watch me go through my pregnancy and have a niece of nephew always in her face, reminding her of the baby that would have been exactly the same age. I feel just sick for her and I wish I could fix it, and instead I am probably going ot make her feel even worse.
And I'm not even supposed to know about this 
Re: Advice on sharing my pregnancy news with my sister...
I am the opposite and my SIL is the one who is due when we would have been.
I would wait to tell her, she may find out later from some one in the family before you tell her and she may be the one to reach out. My SIL did to us through a text.
I felt for us this was the best way because I can not face her. I personally went out so I wouldn't be here when she bought over the kids for Halloween.
Eventually you will have to let her know you are sorry, but I would wait to tell her your news unless some one else tells her.
For me I will have to get use to the idea that she is going to have her baby and I am not going to have mine. It will probably always be hurtful but I have to accept that she is having her LO and I will be it's aunt no matter what.
I don't know if this was helpful, but as soon as she announces this loss out in the open I would some how reach out and let her know she is in your thoughts but hold off announcing yours.
My younger sister is pregnant with her first child. Her EDD is exactly one month after mine would have been.
I'm not going to be able to soften this for you; it sucks. It sucks, and, while I wish her a happy and healthy pregnancy, I can't even face her right now....let alone think about the months ahead. My child would have been the first grandchild on my parents side, and I know that no matter how happy I am for my sister, or how much I will love my niece/nephew, I am having a very hard time getting past the jealous, petty thoughts that: "It should have been me!".
I think the best way to tell her is privately, away from the rest of the family (or when she will have to face them) and well after she is recovered from her surgery. Give her some time to process the information in her own way, and don't be upset if she decides she needs space....not to be a witch about it, but no matter how badly you feel for her, she is going to feel worse and so try not to be offended if she wants some time and doesn't feel like planning a baby shower or being over the moon hyper-happy for you. It's not that she doesn't wish you well, or love you, it's just that she is hurting and needs time to heal and say goodbye to her own dreams of those babies.
Congratulations on your pregnancy OP, I wish you a H&H 9 months!
edit: spelling/wording
That is so sweet of you to take her feelings into consideration!
Ditto what the others said about waiting until she is recovered from surgery and the hurt isn't so raw.
Also, even after you've broken the news to her, please be mindful of how often you talk about your pregnancy. I'm not saying you don't get to talk about it with her, but perhaps for a bit, let her come to you about how it going. The pain will be there for ever, and as someone who is watching my little sister's belly grow (her due date is a month ahead of what mine would have been), the pain does lessen but will not go all the way away.
When I was pg with my first, it was about 4 months after my sister lost her first at 8 wks. I told my sis when I told everyone else, I just didn't share any of my pg with her, until much later in my pg. It turned out that when my sister was coming to my baby shower (about 2 months before my due date and about 11 months after her loss), she called me to announce that she would be arriving at my shower with a baby bump. I was like...how pg can you be? she was 20 wks. She had not told anyone that she didn't see who could figure it out for themself to that point.
My sister is currently expecting her second. Her due date is exactly 4 months before mine would have been. I suffered a loss at Cdn Thanksgiving. She is due around Christmas and my LO was due the day before DH bday. I am extremely happy for my sis and excited to meet my new niece or nephew, but I know when the time comes and that baby arrives, I will grieve for our lo yet again, as I will on DH's next birthday.
I guess I'm telling you this whole story, so you can see that while your Sis will be disappointed and sad about her loss, she can and likely will still be happy for you. You have to tell her at some point and should do it before she finds out from someone else. I would wait until you are through the first tri (my loss was at 11 wks) and give your sis a few weeks to get over the initial shock and grief of her loss, then break it to her gently and offer not to discuss your pregnany with her unless she asks about it. Remember when your LO arrives to be considerate of your sisters feelings and understanding if she has a difficult time being around you and your lo at first.
I think it's great that you recognize this will be hard for your sister to process and that you want to do it in the most sensitive way possible. I ditto a lot of what the others have posted. Definitely tell her alone and separately (before you tell others-you don't want her to find out from someone else). I would also give it several weeks before you tell her....give her a little time to process what she's going through. I would also suggest maybe not telling her in person. It sounds terribly impersonal but it would give her time to deal with her emotions privately and not feel like she has to look happy for you. That way by the time she sees you again, she has had time to process her emotions. (this is how I would have liked to have been told by my SIL-instead of in front of others as a big group-which was just sh**ty).
Little Gabriel: BFP 7/12/11~EDD 3/21/12, miscarried 8/24/11 at 10w