I can't think of how to word this tactfully - I'll do my best, but please just know that I don't mean any of this unkindly.
OP, you mentioned upthread about how a PP wouldn't say such cruel things to you if you had a physical illness - and I think that's exactly the issue. If you had a physical illness, there's no chance of coming back from that - if it were medically dangerous for you to bear a child for physical reasons, it would be a no-brainer.
We don't know your circumstances but you're making quite dramatic and sweeping statements which seem a little excessive. For example, you might be at increased risk of PND but I can't see that you'll be "99.99% likely" to get it. And while medication might be vital to your wellbeing and not compatible with pregnancy, conversations with your doctor might mean there are alternatives to explore. Plus, there is always the chance of recovery with PTSD and mental health conditions in a way which wouldn't be possible with a physical illness. I'm not trying to persuade you to re-think, just observing how your descriptions sound like someone looking for reasons not to have children. No one should be forced to have children, but perhaps you need to re-examine your reasons rather than just pinning it on "medically unable" as that feels a little untrue.
I don't mean to be harsh. I've been diagnosed with severe PTSD myself and have a handful of other mental health difficulties. I don't know your situation but I know mental health problems are awful, all-consuming and overwhelming and I'm not making light of them. At all.
But again, said very gently, you seem quite entrenched in your identity as a patient and as someone who's unwell. You don't seem willing to ever consider the fact that you might recover sufficiently to have children.
I suspect that if you were physically ill, your DH might find it harder to walk away. I suspect that it's the whole package of what's going on, even though you've vehemently denied it at points on this thread.
The bit about him wanting to only parent 20% is a massive dripfeed. If that is factually true and not just about you projecting your anger, then maybe it's YOU who shouldn't want children with HIM....
Aside from all of the above, if this was a woman who had posted about her DH having mental health problems and him not being able to face being a parent, everyone would be supporting her to move on. Children are just one of those things that you can't compromise on. It builds resentment if one of you has strong feelings and the other doesn't. Even if he stays I can't see it lasting, not if he feels as strongly as you say - and deep down you won't forgive him for even considering it.
I'm sorry OP. I hope you find some peace.