The following is an update on the situation I discussed more fully here.
The user who has been stealing my work and slandering me here on tumblr has followed me to deviantart, making an account dedicated exclusively to false accusations of plagiarism! How delightful!
Tumblr user lapetitguillotine is an obsessive creep and I would like to reiterate that their accusations are all false.
Thanks to all my followers for their continuing support.