"I blame myself for not getting to Krissy quick enough that day," Gordon tells DailyMail.com. "I can't blame myself for another addict's addiction but I feel like I failed her."
Brown died at 22 last July nearly six months after the incident for which her court-appointed conservator charges Gordon is responsible.
Detailing the Jan. 31 evening for the first time, Gordon said that when he arrived to Brown's home at 4 a.m. after a night out with friends – contrary to the claims included in the conservator's legal complaint – the star was "messed up," and several bottles of wine were left out.
"Krissy thought I was with some other females and that's when she got upset," he told the Mail. "She called and said I had to come home."
He continued, "I thought she had just been drinking, maybe smoked a little. She was upset, we got into a little argument and then we made up and went upstairs and lay on the bed for about 45 minutes and did what adults do."
It was after he went downstairs to play a video game, he said, that Brown was found by friend Max Lomas. "The Xfinity [cable] guy came and had to do a bunch of stuff in the house and I had my friend Max walk round with him," he explained, adding, "So [Max] walked him into my room to show him the box in there."
Shareif Ziyadat / FilmMagic
Gordon said that Lomas found Brown and immediately called out to him: "I knew instantly something was wrong. You know there's a tone; you can hear it in someone's voice."
Springing into action, Gordon said he dropped to his knees and began performing chest compressions and blowing into her mouth. "It was traumatizing," he recalled, noting that after Brown spit up water he "thought she was going to come round."
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While Brown's family – including father Bobby Brown – point to Gordon as the source of her substance abuse issues, he insisted to the Mail that "she had problems long before I came on the scene."
"They weren't in Krissy's life and I strongly believe they're looking for somebody to blame but guess what? I'm not filling the role of being the blame guy," he charged.
In addition, Gordon shared previously unknown details about his life with Brown and her mother Whitney Houston, alleging that his longtime love had almost drowned in a similar fashion the night before the singer's death in 2012.
He also alleged that Brown spiraled into self-harm and began experimenting with prescription drugs after Houston died, revealing, "she would use drugs to numb the pain she was feeling."
Of their relationship, he insisted that he was one of the only men Brown could trust, noting, "we did everything together." Gordon said that Brown and he were once almost married, and even lost several pregnancies.
"We had a couple of miscarriages. We would have loved to have a kid but we weren't planning on it yet and she was just such a young fragile person it took a toll on her," he told the Mail, adding, "We wanted to get clean, settle down, get married, have kids."