You. Do. Not. Resign.
If they'd like to dig their grave then they can push you out. You still keep your diary. Do not resign. If you put anything in writing to work, you CC in the commissioner and send a copy. However, the only thing I can see you need to put in is notice of maternity leave. Speak to a lawyer about that. Is the nest Slater and Gordon? They're pretty good with labour laws etc.
Do not resign.
By turning staff against you and by them being stupid enough to say things like that they are falling directly into the 'effective dismissal' camp, for which they will be torn apart, especially as you are pregnant!
This new caper will be interesting to introduce into negotiations next Wednesday, for sure.
I love that your eejit boss not only had to pay for a lawyer (I love this so much, that's satisfaction right there!!) but that he tripped his own stupid feet up on his own lies in front of his lawyer - how good does that feel??
Head down, bum up, chicky - this ones yours