I'm not technically widowed because my beloved and I had only started talking about marriage when he was diagnosed with a very fast-growing brain tumor. Our connection was real though. We had intense limbic resonance, a spiritual connection - we could "feel" each other. I could feel it when he had difficult seizures even when we were across town. I was not with him when he died, but I could feel him go. I felt sliced in half and when the phone rang only a couple of minutes later, I didn't want to answer because I knew who it was.
I agree with Stravinsk. You can't describe it. For me it was not like a hole, but rather my identity - who I was, my very spirit - was amputated, like an essential part of my soul was removed. The hardest part was needing him to hold me and tell me I would be okay, but he was not there. No one else's hugs could bring the comfort I desperately needed, that only he could give. Not having him to turn to for company, advice, or just to laugh with. One of the hardest things was two days after the funeral, I went to his house to see his family, and they had already given everything away, and didn't keep anything for me. They managed to find one of his hats, and that hat got me through more days and evenings than you can imagine - I would lay down and cover my face with it so I could breathe him in and talk to him. I had nothing left of him except the gifts he had given me. I wore one of them for a decade after he died, until it finally broke.
The grief was terrible. The worst. But still a small price to pay for the few years we had loving each other.