Why can't I read an external Firewire drive because Boot Camp is broken and my Mac mini 2011 only starts up in Windows 8?

I am running macOS 10.13.6 on a Mac Mini 2011 and I decided to get Windows 8 using Boot Camp. The installation went well, but I can't switch back to macOS (I got advice and managed to fix it, but when I loaded macOS I figured out I made a mistake and Windows was broken. So, I installed Windows 8 again and it worked, but once again macOS broke.) The problem is that I have a 500GB Iomega Firewire drive which was storing just a few photos. On Windows, it just shows 500GB of unpartitioned space. I really need those photos, how can I read them?