For a start, its unlikeley hes got the money to start whinging to the courts about some emails , it will cost him thousands and no one really cares. And if he does, your married, of course you knew his password , and he knew yours !
Why on eath would he really get an order for you to delete them, you can obviously copy it, its an empty threat. Either way, if youve got them, good on you.I did the same and was threatened in a similar way.
I dont know how familiar you are with narcs, but expect lots and lots of threats, most of them wont materialise. If he is mentally unwell there wont even be a question of custody so dont worry about that.
Personally i wouldnt have ANY contact with him , did he hit you in front of your child ? Have your lawyer deal with any agreements, thats what theyre there for.
Divorcing a narc is horrific, theyre not normal and they love to get one over. Perhaps go over to the NPD thread, expect every phone call, conversation and email to be recorded and for other stuff to be used againt you.
Youll get lots of good advice on the npd thread.