I suppose I am a little confused about exactly what you are trying to install using the OEM key. It sounds like you have an Windows 8 Pro install media on a Windows 8 system. If that was the case, the key would not be usable.
As Josephur mentions, if you have an
install.wim, we can apply that image to the OS partition and rebuild your system, just as they do when they deploy installs. If you had a Recovery Drive, or had copied the contents of the Recovery partition to another location, as long as that image was available, the system can be repaired. I have seen information that would lead me to believe the bloatware is in another .wim file, so there is a possibility applying the basic image might allow you to have a system without it installed.
Also, any info about the current configuration would help. From a Command Prompt, you can use
Diskpart to check the drive and its partitions. When you boot the Install DVD, hit Shift+F10 and a command prompt should come up. A camera works well for capturing information you can't capture directly in Windows.
If you decide to go through the process, you will become familiar with the Command Prompt..