Lingard endured limited playing time as his time at his boyhood club drew to a close.
Despite reviving his career with an impressive loan spell with West Ham United in the second half of the 2020/2021 season, Lingard returned to Old Trafford the following campaign to warm the bench again.
The 30-year-old subsequently joined Nottingham Forest at the start of this season when his Old Trafford contract expired last summer.
"I was drinking before bed, having a nightcap," he said on The Diary Of A CEO podcast. "I look back now and think 'what was I doing that for?'
"But I needed something to try and take the pain away and put me at ease somehow. I was trying to forget what was going on. But it makes it 10 times worse.
"You're getting that much abuse, and I'm already down enough, and I've got to perform. I'm already going through things you don't know about. I felt like the world was on my shoulders."
Asked if he had lost respect for United over time, Lingard said: "Probably, yeah. [There was] no balance, no structure, people doing what they want. It was like a free for all.
"They are so behind with everything. You see [Manchester] City's facilities, Tottenham's facilities. People are miles ahead. Even on the social side of things. I went to them in 2017 about YouTube and said let's do content.
"I just want them to get up to date on the new things that are happening. You've got to stay relevant. Catch up a bit.
"You see what City are doing, fresh training ground, best facilities, no one talking back in the press about the team."
