I blame myself for my mum falling out with my sister

[Myl]

My sister was very selfish and did something to hurt my feelings in a family group chat.
My mother stood up for me and confronted her in person. Now my sister is demanding an apology from me and my mother.
My mother can't eat or sleep with anxiety.
I still can't forgive my sister but now she's getting other members of the family to push my mum to apologise.
I've recently been in hospital and not at home to help my mother.
Am I being unreasonable to take time to calm down, recover and ignore the drama?

This sounds quite complicated and as if some family relationships are maybe quite intense/ dysfunctional. Without knowing more details, it’s hard to comment on what you ‘should’ do. But especially as you’ve been in hospital, one course of action might be to say that you need some thinking time, but tell DM and sis that you’ll talk to them both when you’re feeling better. The danger of withdrawing without communicating is that things will fester and build, and that’s how family rifts happen. I know whereof I speak.

Why is she pushing for an apology?

My sister was very selfish and did something to hurt my feelings in a family group chat.
My mother stood up for me and confronted her in person. Now my sister is demanding an apology from me and my mother.

Has sister aknowledge what she did?
Can you share what it was (or something similar)?
How did your mum confront her?

It's very specific incident but I thank you for your reply. My sister is a manipulative person that has a tendency to get a lot of people on her side very quickly and intervention on her behalf.

I'm in recovery and I am texting my mother but not my sister.

I want this to be over by my sister apologising to us both not the other way around.

Sister thinks me and my mother are in the wrong and jealous because we can't just be happy for her. But she completely overshadowed a big life event of mine and ignored my achievements and kept posting about herself.
Thank you for replying

She's pushing because we're "ganging up on her" and won't apologise to her.
That she's sick with a cold and no energy for fighting so now it's our fault she's sick. No mention of my time in hospital.
I hate this drama, thank you for your reply

So you posted in the group chat about your achievement and then she posted in the group chat about her achievement?

What a load of fuss about nothing.

She’s not obliged to gush over you and you’re not obliged to gush over her.

Your mum was a fool to get involved.

What was the 'big life event' you feel she overshadowed with her own news? It all sounds v competitive!