hmmm ring pieces they can be a pain in the arse
sometimes i have just left them off( the ring that is not the nut btw), a mate of mine used to make a die by putting a diagonal cut through a nut if you have a spare, have you knackedered the thread or flattened the end that much you cant get the nut to go on the thread at all.
yes the CV joint will fall off very quickly!!! in my experience.
please DO NOT leave the ring off bad idea. get some pliers pull the ring off straighten it up and press it back in the groove.
hacksaw the end off you should be able to get the nut back on then!