I did install it in a different directory, I even installed it on a different user.
On a proper Operating System, user directories shouldn't be able to touch eachother.
I don't trust many wallets, and keep most wallets in their own Virtual Machine. If you have enough disk space to add another full blockchain, and have some RAM to spare, I recommend to use
VirtualBox for all (untrusted) altcoin wallets.
I wouldn't even trust Virtual Machines like Virtualbox. There are attacks that can tresspass the barriers of the VM and infect the main OS.
If you are serious about your bitcoins, get an additional computer to install dodgy software (and Bitcoin ABC is pretty dodgy in my book). Basically any altcoin software is a potential threat, so get some laptop and use it to completely isolate your main computer is my advice. Once you access the coins, you will be able to delete Bitcoin ABC and get the free space back for the next fork.