How do I cope with the loss of my fiance?

I am 2 years old and was engaged to the most beautiful perfect man. We dated all through high school. He was my high school sweetheart. But he was 2 years older then me. So we continued to date after he graduated. But, a year after he graduated he joined the marines. And...died. It's only been a few months and I don't know what to do. He proposed to me 3 weeks before he died. We we're supposed to be forever. We already acted like a married couple. I was pregnant with his child when I was 17 but lost the baby, so we were planning on having another one later when he discharged cause he really wanted to start a family with me. How do I get better? I see him everywhere, in my dreams. I'm so withdrawn. I can't breathe. Everything that was once so simple like eating, sleeping, breathing, bathing are now a chore for me. I feel like my heart has died too. My family and friends are worried about me, I can tell when they see me. I have shut down completely. I can't take it. Life is so worthless without him. And I've tried my best to be happy. But I don't want to be happy without him. I want him here, happy with me. He always smiled when I couldn't. Always made me laugh when everything was too much. He kissed me and I felt those fireworks. Everything just clicked in place with me and him. I can't see myself with anyone else. I don't want anyone else. He was the one, so now I'm terrified of my future. So much love gone...forever. It's even impossible to listen to music, without breaking down whenever a song he used to like comes on. I took time off from college to grieve and I've been going to counseling but it hurts so bad!!! I go to bed crying every night, and when I'm not crying I feel empty and dead inside. I'm afraid to sleep cause I dream about him. I hate being awake cause he's always on my mind and what could've been. I'm so young, so this is impacting me ten times more I know...but...I will never love someone as much as I loved him. He was my first love and I loved only him for so many years. A week or two ago my best friend thought I was okay with trying to date again, though I said I wasn't, but did it anyway to make her happy. I went out with him and when he kissed me half way through the date I broke down. Right in front of him. Because he didn't taste like my fiance did. Didn't smell like him. When his hands touched me I felt sick. My dates eyes were blue and my fiances eyes were a deep brown. Nothing about my date was like my fiance and I felt sick. My date was a super sweet man but...I just can't. What do I have to do in order to get better? Or at least get free from feeling like I want to shoot my brains out? Time I know helps but it's been nearly a year. How much time does it take to heal? I feel like I'm going to be always broken and always in love with him.... Advice.