In his first interview since a grand jury decided he wouldn't be facing criminal charges, Tony Stewart admitted that he spent three weeks in seclusion following the accident that killed Kevin Ward Jr.

He described those weeks as "the darkest of his life," according to Fox Sports. He was unable to shower or even leave his room. He lost all interest in the world around him; his family, his friends.

"You sit there and you wrack your brain, you try to analyze 'Why did this happen?'" Stewart said. "I made myself miserable just trying to make sense of it ... I just couldn't function. I've never been in a position where I just couldn't function."

Stewart maintains that the tragic accident was just that - an accident.

"I know 100 percent in my heart and in my mind that I did not do anything wrong. This was 100 percent an accident," Stewart told The Associated Press.

Now, after the announcement from a grand jury in New York that stated he wouldn't be facing charges in connection with Ward's death, Stewart is doing his best to move forward.

But he's found it harder to return to the track than he initially thought. He told his team he planned to race at Watkins Glen the day after the accident, but awoke in the morning to the realization that he was in no condition to drive.

"You race hurt, you race sick, and that's the way racers have always been," he said. "You say you can go do what you need to do, and then it becomes very clear that you can't."

Stewart, on advice from his legal counsel, would not divulge what he remembered about the crash.

Ward's family, in the aftermath of the grand jury decision, released a statement saying that "the matter is not at rest," and that they will "pursue all remedies in fairness to Kevin." They are reportedly considering filing a civil lawsuit against Stewart.

A toxicology report showed that Ward had marijuana in his system at the time of the crash.

"You are part of something so tragic and so unthinkable, it's hard to face anybody," Stewart said. "It was hard to wrap my arms around this, and it still is. I haven't been a part of society for more than six weeks. You are scared to be around anybody, you are embarrassed to be around anybody because of what happened."

Stewart knows that no matter where he goes from here, no matter the twists and turns of the next race, of his career, of his life, this situation will always be there with him.

"There hasn't been a day that's gone by that I haven't thought about it. And it will be like that all your life. You are never going to forget about it. You are never going to not see it happen all over again. It's going to be a part of me forever."