I'm so sorry about your loss. Remember, even if it doesn't seem like it, your husband is facing the loss, too.
Men's brains are hard wired differently than women's. To a man, asking how you feel or talking about the pain you're in seems like the completely wrong approach. He's sure that will just cause you more pain, and keep you thinking in endless circles about things you have no power over and can't change. To men, if you can't change it, you ignore it; that's how they feel better. Men are also very action oriented, so to your husband, the proper course of action is to DO domething. That something was looking on the bright side, the fact that you have one healthy baby. He is probably extremely puzzled as to why that thought didn't help you. To him, that seems like the only positive fact of the situation. That's why he's going the other direction now and saying, "Hey, maybe we will have twins," hoping THATY'S what he should have said first. When that thought doesn't cheer you up, he'll probably get very grumpy and unresponsive, NOT because he doesn't love you or because he doesn't feel the loss of the baby, but because his best attempts at making you happy again have failed, and he doesn't know what else to do. Men do not understand why you would keep thinking about something that hurts.
A girlfriend would instinctively gather you up in her arms and cry with you while you told her how much it hurts. Men cannot understand that, because to them, it looks like that is making the pain worse. Tell your husband, VERY clearly, what you need, or he'll continue to be confused and do things that irritate you. He may say things like, "How will that help?" or "That won't change things," when you explain your need to discuss your feelings. Be prepared to explain, "This is how I can feel better, even if it seems strange to you." Assure him that when he listens, or says, "How are you feeling?", it DOES help. Remember, too, that he needs you right now, just like you need him! He's just no good at telling you that, because he's a man.
You can always honor the memory of this baby AND be happy again. It doesn't seem like it now, but you WILL feel like yourself again. And, you'll be able to help other moms, because you'll know how they feel. God bless!