Ex-friend contacted me after years of silence after I called the police on her

Four years ago I had a friend in a downward spiral. We lived on opposite sides of the country so I could not do much except support her over the phone. She was crying and panicking every day with being overwhelmed by her two kids who were only 1 and 3 at the time. She was cheating on her husband with random men she met online. She started locking her kids in their room and she would put on noise cancelling headphones on to go to sleep for HOURS. She’d forget to feed them. She wouldn’t bathe them for weeks. One day her 3 year old wouldn’t stop crying and she texted me she was going to “kill her child or kill herself”. I had no other options but to call the police. She obviously knew it was me and that was the last day we ever spoke. She blocked me on all platforms but I did not try to reach out. That was her choice. I have no idea what happened afterwards.

This morning I woke up to this message. I haven’t a clue if I should respond or if I should let it go. I don’t understand how she can’t grasp that I had no other choice. She threatened to kill her 3 year old. I’m in a different state. She had zero friends or family near her that I could contact instead. I did not have her husband’s contact info. I did not want to delay and have her child end up murdered. If you were me, would you respond? What would you say?