Ok I'll even top that. If you can't even trust your gf to not run file recognition and recovery software on your computer, then why even be with her. Without trust there is no relationship.

But to answer your question at least partially. If you delete the files and any incompletes, which incriminate you. Then run cleaner software e.g. ccleaner deleting all temp files, autocompletion etc. and run a registry cleaner to get rid of any references to said files, then odds that she will go further than that are slim to none.