IMO he's an irresponsible selfish nob.
Unless you have significant savings which will last you realistically until his business gets going I don't know how on earth he thinks the bills will get paid ?
And presumably that's not the case or else you'd have mentioned it ....
It's also insulting to your parents as it makes their loan being repaid less likely.
How you deal with it though is beyond me as you literally can't stop him.
I guess you could give him an ultimatum maybe ?
Flinging platitudes at you is NOT good enough ..... 'trust me' and all that. His business isn't bringing money in yet .... when is it likely it will ?
You'd be better able to trust him if he explained HOW it was going to work and in order to have your blessing for this he needs to show you (based on any savings, other income (?) etc) how the bills will be met each month, how long you can sustain that and so on. Anyone determined to hand in their notice and wanting to get their OH on side would, I'd have thought, automatically reassured them that this could work, based on cold hard facts rather than silly throw away remarks which are worth sod all.
Makes me really angry that he's stressing you out over something like this when you're heavily pregnant.
Fair enough he doesn't like his job but he needs to work out a solid, sensible, and responsible exit plan before burning his bridges.
This almost smacks of him having, in effect, a tantrum because 'it's not fair' you're at home and he isn't (and in a job he doesn't like). Do you think there might be an element of that to this ?