The England Under-21 international was a top target for Spurs throughout the summer, but no deal came to fruition.
Per reports, Spurs' first bid for Grealish was worth £3 million plus young midfielder Joshua Onomah, and Steve Bruce subsequently claimed that the Premier League club were "nowhere near" Villa's valuation.
Grealish signed a new contract at Villa last week, having spent his entire career at the Championship club, but he has now opened up on the transfer falling through, admitting that his head "was all over the place", and his feeling that the move could have opened the door to the England squad.
"Of course there's going to be disappointment there," he told the Daily Telegraph.
"I felt that if I'd gone there I could have maybe been in the England squad by the end of the year.
"At the start of the season, my head was swivelled. Even after the transfer window closed, until the end of August, I wasn't right."
Villa were struggling with financial difficulties throughout the summer, to the point that the 23-year-old had accepted that he would be leaving the club.
However, he insists that he is fully committed to the club.
"I thought I was leaving. Before the new owners, Villa needed the money so I kind of accepted that me going would save the club," he added.
"It's not like I was devastated it didn't happen, though, because I've still got to realise how lucky I am to be playing for my boyhood club. I've played over 100 games for Villa and I've only just turned 23."