Advice? Worried about breaking pregnancy news to friend having IVF.

Hello all! Wasn't sure where to post this to get the best advice. Hope it's ok here. One of my best friends has an autoimmune condition where her body attacks the baby if she gets pregnant. She has to have a lot of treatment prior to ttc via IVF & continued treatment throughout the pregnancy (lots of injections and intravenous drip medication), she has a perfect little girl who they had through this treatment & IVF after 5 years of trying/losses/tests/failed rounds and she is almost 3. They are currently going through another round to conceive her a sibling. I lost my first in May last year & she was a massive support to me, I was very lucky to fall pregnant again almost immediately with my daughter who was born in March this year & we are exceptionally lucky to have fallen pregnant again with our 2nd (I'm 11 weeks and baby is due April 17). She is usually someone I would tell immediately (I did with my daughter) even though we are very private & plan to announce publicly very late into pregnancy but I haven't told her because I don't want to upset her. I feel guilty that it has been so much easier for me. No one knows I am pregnant again. Do you think she will end up more hurt if I continue to keep it from her whilst I comfort her through her shaky IVF journey or if I tell her? We currently don't plan to tell anyone (even parents etc) until 16 weeks (when we find out the sex) or for as long as we can get away with it. Sorry for long post. All advice welcome!!