Op, I don't wish to second guess you at all, but I'm going to ask only the basis of what you've written so far...
Are you sure divorce is what you want, or you reaching out for it because you desperately need something big to change?
It's just, you're being treated for depression, you're clearly drowning under the drudgery that comes with early motherhood and you sound so lost, so numb...I'm just wondering if you're projecting at all?
Forgive me if I'm hugely mistaken, I've seen how desperately unhappy marriages can make people, but you haven't mentioned your husband much. Most of your anguish seems to be around your role as a mother.
There's nothing wrong with that, of course, it's so normal for women to feel the same way especially with infants of the same age. But I've also wondered whether pnd has played a part in leading you to this point of desperation?
How did your dh react to you saying you'd like a divorce? Have you spoken about you feel?
Hope I've not offended you 