As a minor note to this, the NSA doesn’t necessarily need to know your private key to decrypt e-mails sent to you, it needs your private key, or the pair to the key the the encryption key for the e-mail was encrypted with, if the sender wants to keep the e-mail in a form that they can access later as well, without retaining a plaintext edition of the e-mail. It may be easier to get that than to get your private key.
