I lost one of my girls yesterday to heat stroke and I’m all torn about it. Should I keep other 3 out of coop?

Disclaimer -
Chicken owner for like 10 months so I’m still learning, and don’t know what I don’t know kind of thing. I know some will beat me up and it’s probably deserved but I’m already doing that enough. I have now read a bunch of tricks to keep them cool, that I clearly should have researched before yesterday. To my fallen girl, I am terribly sorry for failing you. Very sorry.

Question -
I’m scared to give the other 3 coop access now until I make some improvements. I’m thinking to keep them permanently in the run until I add some fans & a kiddy pool. Am I overreacting? Is my fear of the coop valid? It’s now just a dangerous death box in my eyes.

I made them sleep in the run last night because they were panting in the coop at 9p, but now I’m just scared about predators. I guess we will always be worried about something, but if they will just sit in a hot coop against their own best interests and die… then I’d rather they stay out of it.

Backstory -
Found her in the coop doa. I saw that she was struggling earlier in the day but she’s been broody, so I thought she was just going through an episode that usually ends once I remove the eggs. I brought the water to her, she sipped a little but not as much as she usually does. I thought that was strange but figured she would drink more if she really needed it.

The other 3 were out of the coop but she stayed (with water). It was very hot in there, but I just told myself she’d probably join them shortly. I heard her yell as I walking away and that’s the part that’s really fucking me.

I could have saved her. I should have saved her. She cried out for the only person that could save her, and I kept fucking walking away. I just didn’t know she was in such duress & wouldn’t try to save herself. I feel like shit and hurt a little every time I look back there & see 3 birds instead of 4. They survived such a brutal winter, just for 1 to pass away the first day it hit 90. I just told my friend how proud I was that they’re thriving and almost a year old. Then boom. Fuck.

Part of me posting this is just to share with others that can feel my pain. Thanks for reading.