D.M.
L.,
I am the product of a vanishing twin pregnancy, and I am just fine.
My Mom in fact talked about it with me when I got pregnant and they suspected I was having multiples. But, it was just a strong heartbeat.
What I learned from my Mom was that it was tough for her to 'stop' thinking about my 'twin'. She at first, like you, was relieved that there was only me. But, she said overtime she came to feel grief and then, anger that she was relieved. I think it's normal to experience the grieving process in these situations, and to let your emotions be felt as regularly as possible. Don't squish them away and pretend they aren't there. But, one thing my Mom said she struggled with until she finally did talk to her doctor was placing 'blame' on herself for the loss.
It's not your fault. It happens quite regularly and is very common. What my Moms doctor recommended she do is talk to someone about her grief, a friend, therapist or someone else. He also recommended she begin a journal to track her feelings of joy about the baby she was carrying that was healthy and flourishing.
I love that journal, because she gave it to me when I found out I was preggers and it is one of my most treasured possessions. I wrote one with my son, and will pass it on to the next generation if I have a girl or to the Mommy of his kiddos.
I think the best thing you can do is feel your emotions, and find a healthy way to release the sadness. Talk to a friend, your Mom or a grief counselor (they are usually on staff at many hospitals) that can help you express your sadness and move forward.
I think it's very brave that you are admitting your sadness inspite or your joy, and that it's a great first step to healing.
Best wishes and congrats and the Baby!!
D..