I have an incurable illness

Hello, 3 weeks ago I learned that I had an incurable illness that I would have to endure for the rest of my life. I haven't told anyone about it except my mom. I turn 20 in a few weeks and learning that I have health problems that will impact my entire life is shocking to me. I need to tell my family about it but I don't know how... I don’t know if I should tell them about it in the family group on What’s app that we have and I don’t know how to announce it… I need others to know, I feel alone in my illness but no one checks on me except my mother. I need support, but I don't know how to tell them that. Should I tell them IRL instead or should I send the damn message to the group? I am lost and alone.