As a JW you learnt that it wasn't safe to be yourself, it wasn't safe to voice your opinion or share your true feelings.
So you developed your own ways of dealing with that, like defensiveness, deflecting, dishonesty etc etc.
Sounds like your wife is inviting you to be yourself, she's letting you know you're safe with her, she's not the elders.
Being yourself takes practice but it's worth it and it sounds like you have already figured out what you need to do, so just relax and everytime you feel yourself going into WT/cave-man mode take some deeep breaths and say "honey, I feel.......and I think......." and then listen to what she has to say. Maybe even ask her how she deals with the same feelings. Believe me she will thank you for it and it will get easier.