Holy shit. He's put you in a position where the only way you can enforce your marital rights to shared assets is through divorce. Ironic understanding of marriage, huh?
The thing is, he did marry you. He didn't have to do that, not doing so would be more in keeping with an idea of keeping assets separate. He must have had some trust and intentions towards togetherness.
Your first step is to have a proper conversation with him, pointing out what marriage means and that (unless legally protected) all assets are shared - whatever fanciful notions he holds in his head. (Even his will only kicks in after death, not in divorce).
Then on to this being a child of this marriage, for whom he has equal responsibility - and love, surely? (It sounds very much like he thinks he's doing you a favour by 'letting' you have a child, of your own. Who paid for IVF?).
Then onto your expectations for the future, his responsibilities, what is reasonable, what isn't and how you want parenting to be shared.
Practically, you will receive child benefit. You should qualify for statutory maternity pay.
Realistically, based on freelancers I've known and the realities of childbirth, taking 3 months off seems tenable.