Sorry for your loss NASA, hope it recovers well for u. It's easy for me to say but try not to let it get u down to much. U did as much preparation & research in everything on your build as anyone could have so everything went well once setup. Dont let one thing kinda overlooked discourage u, I know it's hard with all the work u put in on the build.
I would recommend heaters that have a internal thermostat & like they already mentioned, turn it a couple degrees higher then your apex as a extra failsafe. I know that's not what your issues were but I'm sure u will be implementing more failsafes. I don't have a apex so I have my heaters on a inkbird controller & I love it. I went forever with no failsafes on my heaters but I was lucky I never had issues. It does make me feel better having it on the controller with the heater thermostat as a failsafe.
Again, so sorry for your problems but try to have a merry Christmas