Thank you so much. 20 hours and actual sleep later I realised I put 2.18 instead of 2.19 in my first post, oops.
I've added an exception to the folder with Sugarcube 2.19 in it for now so I have that up and working. I just wanted to know it wasn't going to cause me problems, you know?
I have no idea why Windows Defender decided this was something to screw with me over, but there you go.
Thanks every so much for your swift and helpful replies :)