Unfortunately there are some unfriend-lies out there even in your own circle who doesn't mean your work or progress well. Sometimes even a service account has been used to peer in and worse. Is there a way to hide/safeguard dev work ( SP 2010 Workflows, sub-sites and InfoPath forms ) only meant for me to finish , away from those folks ( in any shape or manner without breaking paths too much ) before completion and unveiling .
Outside of your own Dev environment like Marek suggested, you can hide things by keeping them in draft mode - so if you're creating a new sub site, don't check it in (in the case of a publishing site at least) just hit save. You'll still be able to browse to it, however not even site admins will be able to see it.
Same with workflows and Infopath forms - hit save, but don't publish. It makes it incredibly hard to test however, because you will need to publish before you can test it properly.
Sounds like you're in a terrible situation, and I'm sorry to hear it.