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You are looking at both potential criminal actions (although this may be very tenuous (unlikely)) - see: http://statelaws.findlaw.com/california-law/california-extortion-laws.html), and civil causes of action for defamation (much more likely) - see: http://www.dmlp.org/legal-guide/california-defamation-law.
As a practical matter - sending a threat such as this to simply force another person to call you is not a very wise course of action.
Threatening someone to go see a therapist or you will send your proposed email is almost certainly going to result in action against you (potentially even get you a civil restraining order being taken out against you (if I were counsel for the individual you are threatening, I would definitely recommend it) - this can result in ongoing problems for you, including taking away your right to own firearms, requiring you to disclose this in future legal proceedings (as well as applications for jobs and licensing - far into the future).
I cannot provide you formal legal advice or instruction on this forum, but I think you may want to reconsider this email (you probably are already doing so - hence asking the question). Do not threaten people like this - it will never result in the action that you are hoping for, and very likely will end badly for you.