Lost one of my twins..

Had my twelve week ultrasound today.. Baby A had stopped growing at 8 weeks. I saw it and it was tiny with no heart beat.. Baby B is healthy and waved at us.. I don't know how to feel right now. I have been crying the past two hours but now I just feel confused. I'm grateful one of them is ok and we will still have our baby. But knowing it's twin is still in there and not alive makes me feel empty somehow.. I don't know what happens now, my specialist will call me tomorrow. I assume I can't have a d&c because of the risk of harming the other baby. But I'm not passing it on my own. I have had no abnormal cramps, no spotting even. I had no idea anything was wrong. I was so excited to see them today. I don't know how to feel. I just feel sad.