Yeah, don't go to HR unless you have incontrovertible evidence that your boss is a pedophile or Islamic extremist about to blow up the building or something similar. HR will choose the company over you unless the situation would be so damaging to the company that they have to do something.
Planning an exit strategy should be first on your list. Life is way to short to work for d**heads. I have twice left companies after similar periods of time with no long term repercussions, so don't get too bent about this.
Second, when your little one arrives, you're not going to be able to put in 55 hour work weeks. Can your boss fire you or would this leave an irrecoverable hole in his team? If not, plan on a calm, passive aggressive strategy at work. Do the stuff that's the most important. Stay frosty. Get home and support DW at a reasonable time. It's just a job, and apparently not a very good one.
If your job is at risk, do you have a good supply of FU money? Reconcile yourself to spending this if necessary. If employment laws are reasonably pro-employee investigate how to get the most out of the company in the event your position is terminated. Consider an employment lawyer.
What about parental leave legislation? Some areas have mandatory parental leave law - if you apply for parental leave the company has to approve it.