Bebe, really sorry to hear that your discussions haven't gone well, I was really hoping they would. I can understand in some way what you're going through, as discussions on the issue with my DP on holiday reached the same kind of horrible dead-end several times, and in a similar way we've been forced to look at whether there's a point we decide not to be together anymore if we want different things. (These issues are still rumbling on without resolution) It's terrifying and horribly destabilising in our situation and I can only imagine it's worse when you are married with a child in the equation.
I think people above have said some really sound things. I'd echo WhyWait and say that you shouldn't have to dance around the fact that you feel really sad to him - it's fine to say, honestly, that you're feeling terribly overwhelmed by what's happening between you and that's why you're appearing to be silent/'off'/whatever. You're not intentionally punishing him.
Echoing Squirrel too that unfortunately if someone doesn't want a child, then that choice has to be respected, but equally, he should do everything in his power to make that choice an OK thing for both of you, together. You need to understand that choice, so he needs to put the emotional work in to provide you with some sort of explanation to help you to an understanding. (Yes AC we are def right on this one).
Maybe his suggestion of separation is because he doesn't feel good enough for you, feeling the way he does? Just because separation has been mentioned, doesn't mean it's anywhere near needing to be a reality. Maybe there's something good from having that alternative life possibility out in the open, even if neither of you wants to take it?
The final thing I wanted to say (and again, I'm no psychologist) was that I wonder if your DH's depression is underlying his feelings on this? If he feels (even without logical reason) inadequate, unsure of his ability to provide for you because of the financial issues, frequently stressed, under pressure, and/or frightened of your potential illness/the illness of a child (however irrational those fears) - well, those aren't the conditions that make you full of hope and optimism and eager to bring a new life into the world. On a purely animal level, stressed animals don't breed! Maybe that might be oversimplifying, and it certainly can't help you with your frustration - but maybe those feelings might also change in the future?
Final final thing - don't worry about spouting off on here, it's what we're all here for.