CS5 - has it stopped being supported or?

Let's try PS first. Try resetting your Photoshop preferences. Press and hold Option+Command+Shift (Mac OS) immediately after launching Photoshop. You will be prompted to delete the current settings.

Might help, might not but as others have said, CS5 has no more updates or direct support from Adobe.

That multiple (old) Adobe app's are not working points towards some issue on your Mac.

Try logging into another account (you may need to make one), still crashing? 
Try starting up in Safe mode (hold down Shift Key when booting), still crashing? 
You might want to try running a free utility like Onyx: still crashing? 
https://www.titanium-software.fr/en/onyx.html
Also view:
https://www.macworld.com/article/352902/onyx-review-macos.html
https://www.macworld.com/article/224955/how-to-reset-a-macs-nvram-pram-and-smc.html
From Adobe:
https://helpx.adobe.com/photoshop/kb/basic-troubleshooting.html

Adobe stopped supporting CS5 years ago, I think some time around when Creative Cloud appeared so it'll be at least 9 maybe 10 years...

CS5 basically stopped being supported in 2012, about ten years ago.

I assume High Sierra hasn't seen much in the way of technical updates either in the last couple of years, so you should look at anything that has been updated. Anything that has changed in the environment. In the meantime, reset preferences to restore the application to factory state.

Generally, if you choose to stay with old software you need to deep-freeze everything. Don't update anything.