Well, I'd say that the financial situation sounds pretty standard for a new business - if anything, it doesn't seem to be going too badly, if he can pay rent and food bills. It does take a long time to get a business going, and before it makes a reasonable level of money. Running a business is not a sure-fire way to make money by any means. As he says, you can put bills in, but customers don't necessarily pay. And of course, you weren't expecting a baby when he set the business up.
Is the problem really that you don't think you ever agreed to offer him the financial support that he needs to set up a business? That he set this up without telling you it would potentially have a major impact on your lives? You do sound very angry with him for setting up the business, and I do empathise with you about that. It is a big financial responsibility for you, and should have been a joint decision - but I wouldn't be surprised if your partner never realised it would be as hard as it is. Is money really all that's at stake? Is he spending less time with you than you'd like as well, for example? What's more, it sounds really important to you both that the man is the main provider - you're both feeling that he's failing in his role as a man, just at the time when he's going to be taking on new responsibilities as a dad.
It sounds like you want him to find a full-time job and give up the business. Would this actually be possible? Is he likely to be able to find a job? Will his current business be an asset on his CV or a liability?
If he finds a full-time job, plus your baby, realistically he's going to need to give up the business. Is he going to fill happy with that after all the time and money he's put in so far? Would you feel happy with that?
If he wants to keep the business going, would you rather stay with him, or end the relationship and find someone new?