'Pregnant Man' Thomas Beatie -- One Rambling Email and My Ex is Going to Jail

Ex "pregnant man" Thomas Beatie says he's living in fear of his ex-wife, and their relationship is so volatile now ... a judge is even limiting their emails to about the length of a tweet ... TMZ has learned.

Beatie claims his ex, Nancy, has waged a 2-year campaign of threats and harassment against him ... ever since they split as a couple.

In court docs, Beatie says he testified against Nancy last October for allegedly violating an earlier restraining order. After the hearing, Beatie claims Nancy flew into a rage ... scaring him so much he immediately sought a SECOND restraining order.

In his petition, Beatie wrote, "[Nancy] is here now outside the room from me as I fill out this second order against her. She is very angry and verbally assaulting both me and my girlfriend."

That was enough for a judge ... who ordered Nancy to stay away from Beatie's home and workplace ... and limited her to 2 kid-related emails per day.