I'm sorry to hear that, and I understand how you feel. I do agree with Mom2pride though, you will find another amazing horse. There will be many more to cross your heart, as long as you open it up to them.
When I sold my Trakehner mare that I bought green-broke out of a field and trained up to schooling 3' hunters, it was really hard. I cried for about a week straight, with my amazing husband holding me and just letting me be a big baby. I sold everything I owned, and didn't so much as look at a horse for a year. It was a really rough period, and I do still regret selling her. She was my entire world, and the best horse I've ever had.
But then I couldn't stay away from them, and got back into riding/training. I have now found, several years later, my new guy and as much as I try to compare him to my mare and be sad, he pushes his way into my heart and he is there for me. He is phenominal, and is really showing me that there is such thing as loving another horse after you've thought you lost 'the one'.
You will find another horse, who is going to love you much the same, unconditionally. No, it'll never take the place of your horse now, but it will be a whole new kind of love. I promise. :) It is like loosing a loved one. We never forget, but we learn how to love again.
...he's so kissable, huggable, loveable, unbelievable...