My wife has multiple sclerosis. Fortunately, hers is of the relapsing-remitting variety, which is one of the milder (in the long term) ones, and her treatment is doing wonders for her; she's only had two relapses in the last 7+ years, and she's doing great most of the time (her only persistent symptoms are slight weakness in the legs and moderate loss of sensitivity in several body parts).
A semi-distant family member of mine (mum's cousin's daughter or something like that) had a much more aggressive version of the disease and just passed away from it. She was about the same age as my wife, but she was confined to a wheelchair, needed help to do most things, had trouble speaking and looked unhappy in general.
My wife and she were not best friends forever, but they were on friendly terms and my wife always asks my other family members how my mum's cousin's daughter is doing when she visits my family (which she's planning to do in a couple of months; my family lives in a different country as us).
I want my wife to hear the news from me because she's going to hear it from someone else eventually and I don't want to have kept a secret from her (we don't keep secrets from each other). At the same time, I can imagine it must be pretty difficult to hear that someone (and not just some random person in a different part of the world, but someone you knew) just passed away from something you have too. I don't want to upset my wife (stress can help set relapses off, and my wife is also prone to anxiety attacks; no matter how benign her version of multiple sclerosis is or how much her medication is helping, stress is terrible for her).
How do I go about telling her this?