Ohhh Dear...1st let me say well done, your a strong woman and I am proud of you. With your strength by your husband's side that in itself is a great cure mentally for him and your sister I guess should focus on the blessing of her child. I cannot provide any practical help But all I can say and do is to keep you in my prayers. Only GOD can turn the impossible into the possible so stay strong and tell him your worries and leave it up to him. Your a great Wife and Sister by the sound of things.
Take care and May GOD grant you all your wishes.
Love Dx