How do I process my sister possibly being a murderer?

To make a very long story short, my sister was arrested for murder a few months ago & up until today I was pretty confident she was innocent solely based off her character.

She's quite a few years older than me. She was already moved out by the time I started school. We weren't exactly the closest, but I don't think anyone could ever look at their family member & go "yup, totally saw that coming". But, I just learned today that the evidence they have against her is pretty concrete.

I don't want a whole lot of details out just to protect my privacy (I don't get this luxury IRL. It's a really small town-population is less than 900-so the amount of shit I get already is more than enough to handle. I'm aware posting family business online isn’t exactly private but I literally have no one to talk to about this), but there's no way to explain the evidence they have on her as anything BUT my sister (allegedly)killed this woman. DNA doesn't lie.

She's officially plead not guilty. I wrote her a letter after she was arrested asking her what happened (I didn’t expect a confession, I just didn’t expect it & found out she was arrested by seeing her mugshot on the news) & she wrote me one back swearing up & down she was innocent. l'm just not sure what to think. I know it's not my job to believe or not believe. The police said she’s changed her story a bunch of times.

If I feel this shitty I can't even begin to imagine how the victim's family feels...

I'm honestly not sure how to process this information. I'm just physically sick to my stomach & very confused. How do I even begin to process this???