Well we are in a bit of a pickle arnt we!
I dont know what to suggest, it is obvious your very responsible, very ethical and very loving - but most of all there is a obvious increase in health risks.
I think its going to be a very hard choice but here is my two cents worth from what I would do.
Having three kids already, that I found hard to cope with keeping the child would be, unlikely
believing abortion to be wrong not only for myself but for the child too, abortion would be out of the question
so I would have to give birth unless the health risk seriously threatend my life, then I would have to reassess the situation again but so far I am giving birth and bravely giving my child to a loving couple who I would choose to raise my child as their own - adoption maybe hard but I think it maybe the best option all round, for you and your husband at this difficult time, the child and the childless couple... Thats how I would be thinking anyway.
Btw - congratulations on your husbands release, I will pray the rehabilitation works and your never seperated again.
God bless
izzy