I'm feeling pretty reactive now, so this may not be the best response you get...but, is it time to get your L involved? Maybe have your L send him a cautionary letter. Documenting that you are unable to even communicate with him directly because she controls emails, documenting that he threatened to take the children to Russia (who cares if he means it, he said it); documenting your rights to know the children's whereabouts, word-for-word, from your separation agreement?
For me, it would be worth the hour or two of L fees just to hand it over to my L and say send this a** and the a**ette a letter.
OTOH, I'm pretty ticked myself tonight, so let's see what others think.
