The Dutchman felt his Blues side should have taken the game away from Sunderland having regained the lead just before half-time.
But they found Vito Mannone and a resilient Sunderland defence standing in their way after the break.
Fabio Borini and Jermain Defoe then scored twice inside three minutes to seal a dramatic comeback in front of 47,050 buoyant fans at the Stadium of Light.
Hiddink said: "Disappointing result because we like to win every game, which is not always possible.
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"When we analyse the game, we should have had the score more in our advantage.
"We played very well but by not scoring our chances we then invited them into the game.
"We reacted to make it 2-1 but the second half we also had two or three open chances and didn't take them and they got new energy.
"First half and part of the second half they were a bit shaky waiting for the kill. We didn't do that though.
"They were very well supported by their crowd to help make the win, this was a huge win for them."
Meanwhile, John Terry could have played his final game for Chelsea following his sending-off.
Terry was dismissed for the second time this season and the sixth time in the Barclays Premier League for two bookable offences late on and will now be banned for the midweek trip to Liverpool and Sunday's visit of champions Leicester.
As a result, the 35-year-old defender, who made his debut in October 1998 and is out of contract this summer, appears to have pulled on the blue shirt for the last time after revealing in January that he would be leaving Stamford Bridge.
The club has insisted an offer may be forthcoming, with incoming head coach Antonio Conte having a major say in the final decision, but there has been no sign of one so far and current Hiddink remains uncertain over the former England defender's future.
Asked if Terry's appearance on Wearside would be his last, Hiddink said: "For the club, I don't know, but it's sad, of course, that he was sent off for a second yellow, and it's the second sending-off, which by the rules means he will suspended (for both games).
"I think the referee [Mike Jones] was too close to the incident. Normally we say, 'Referee, be close to what can happen', but I think he was too close and an impulsive reaction made him draw the yellow card.
"With a little bit more distance, 10 yards more, he could have thought, 'Hey, these two guys went intensively for the duel' - it was an intense game and he has to consider a bit the intensity of the game and this duel as well.
"He was too close, for me, and took too harsh a decision."