I completely understand how you feel and how it feels to be sick, pregnant, caring for a child and doing a shift as a single mom. I had to make the horribly tough decision to terminate my last pregnancy while my husband was in Africa on a trip (made the decision without him, went through it without him, had a child at home to care for through it.) when the docs told me I might have cancer and would have to forego treatment if the pregnancy continued or I would have to abort later. I would not wish that position on anyone. Not Anyone.
If the trip is elective, I would feel the same as you: Abandoned by the man who is supposed to care for me and his children when we need him most.
BUT I gently encourage you to see this from his perspective. It's possible that he is completely freaking out. The woman he loves and his child in her womb have a life-threatening disease. He might fear being a widower, especially after your scare with the non-response to the treatment. He's probably out of his mind feeling helpless to give you what you really need -- a cure. Does he have a support network? I know it might be hard to have a lot of sympathy, but caregivers need support, too, especially a man who is not normally the one who fills the role of nurturer. He's imagining what it might be like to be a single father, lose the one person who keeps him grounded and sane, whom he loves with his heart and soul and lose the mother of his child(ren). And he doesn't want to think those thoughts. He wants to run from them, push them down, so that he can be strong for you and the babies.
Men provide. He has a job which pays the insurance and the home and all the other stuff that gives comfort to and meets the needs of his family. Maybe he feels like he can bury himself in providing for you. He probably knows that's some sort of a cop-out, but men feel helpless in these situations and he's grabbing for his role, you know? He probably also needs to get away from the intensity of it all, to calm his nerves, so he saw and opportunity to be both provider and escapee.
Is he the sort to abandon ship or is he suffering, too? I know this is hard for you. Is there any way you can find a caretaker/ friend/ church member/ neighbor to come in and help with your daughter and check in on you while he is away?
I guess I just really feel for both of you. I hope that things turn around very soon and you have your health back. I will pray for your family and the new life growing inside of you. I know you're scared. I'm sending you strength.