I attempted to change my control arms yesterday, and I know that for the front one to be removed, the cv axle has to be popped out (otherwise there is no room for the ball joint to be removed). So I tried to remove the center nut, but I couldn’t, even with a breaker bar. Not having the identical and proper e-torx socket, I was reluctant to apply more force, especially since I started to wonder if it is threaded the other way. The last thing I want is to keep trying to remove it, only to actually be tightening it even more... any help?

All axle shaft hub nuts are right hand thread. Righty tighty lefty loosie.

These nuts have the highest torque on the vehicle. And are single use nuts, they need to be replaced once removed. And the torque spec is multi step.

Hmmm... we replaced the front control arms last year and re-used the nut...

I believe you. MB says to replace it.

Most manufacturers suggest replacement. Sometimes I do and sometimes I don't. Usually not because the cost is nuts.