

I suddenly resigned by email and now my manager and the office manager won't stop messaging me
I've been at a small company for 7 months doing admin/data entry work. Honestly, I was really struggling mentally there. The atmosphere in the place is not good at all, and I kept telling myself to endure it, get through it, and not make a big deal out of it, but recently it became more toxic and honestly close to verbal humiliation. Most mornings I'm already anxious and waiting to see what will happen next. There were also some personal issues piling up on me, and a few days ago I finally decided that I couldn't go back there again.
Early today I sent my manager an email with my resignation, effective immediately. About 3 hours later he sent me a text saying: "Hey H, what happened?" And now the office manager is also messaging me and asking if I'm okay.
What am I supposed to say in this situation? I'm anxious that they'll start contacting my sister, whom I listed as my emergency contact, and try to get information from her. I still haven't told her the whole story. I probably should have chosen someone else for that, but am I required to answer to my former manager or the office manager at all?