Announcing to sister in law with fertility issues?

Hi so my sister in law who I’m very close with has had 3 miscarriages, many failed IUIs, and will be starting <a href="https://glowing.com/glow-fertility-program">IVF</a> very soon. She is a VERY sensitive person and I’m not sure how to tell her that I am pregnant. She said she’s going to start the <a href="https://glowing.com/glow-fertility-program">IVF</a> process Feb 5. Do I tell her before she starts the process or during? She has mentioned in the past that if I were to get pregnant she wouldn’t want me to tell her in person because she doesn’t know how she’d react? Any advice will do as to how/when to tell her. Thank you.