He didn't feel like celebrating. The rest of the world rejoiced as he mourned. Everything he had ever had, ever loved, was lost. Gone, forever. The amber liquid burned as he knocked back glass after glass but he welcomed the pain, almost as much as he welcomed the relief the alcohol brought him. He was no idiot – quite the opposite in fact, he was one of the brightest in his year. He knew that the drinking would only delay the agony, could never fill the void their departures had left him with. But right then, in the dark, dank shack with the distant celebratory fireworks providing the only break to the velvety blanket of the night, he did not care. He was no longer the smart, sensible, loving prankster he had once been. He was broken.
No pain, and he knew pain well, compared to this. The complete wrenching of his soul, the ripping of his heart. They had left him, alone, in a world full of ignorance and hatred. And in that moment, as he hit rock bottom and drained the last drops from the bottle, he hated them too. Not for leaving him, but for making him love them in the first place. He had been quite prepared for a life of solitude, he thought his condition saw to that. But they welcomed him with open arms, accepted him as him. More than that, they loved him, were his brothers, his family. And now they were gone. All of them. He wished they hadn't bothered. A lone tear slowly traced its way down his cheek and the empty bottle fell to the floor from his slackening grip. The alcohol was beginning to take effect, and he welcomed the empty blackness like an old friend. Not that he would ever do that again, he had no friends left. The exodus had come and gone and he was left to suffer in its wake. Whoever said "it is better to have loved and lost than to have never loved at all" was a real arse.
A/N
I don't think anyone can truly comprehend the immense lost Remus suffered with the first fall of the dark lord. James, Lily and Peter dead. Sirius in jail for life for their murders. Harry taken away. All never to be seen again. I honestly don't know how he didn't just give up.