With two games left going into Tuesdays night's clash at Arsenal, nothing short of victory was enough to save Roberto Martinez's team from the drop.
But despite fighting back to 1-1 and a few bright moments after the interval, the FA Cup winners lost 4-1 to confirm their place in the Championship next season.
Jewell, Wigan's longest serving boss between 2001-2007 who steered them into the top-flight in 2005, said: "I'm very very disappointed.
"A lot of people are saying it's the end. It's important after all the hard work that's gone into the club over the years and the progress they've made to realise that despite this setback, it's not the end of Wigan.
"I don't know what's going to happen with the players and the manager, but it's a time for reflection having been in the Premier League for eight years and winning the FA Cup on Saturday.
"It used to drive me mad when people would pat us on the back after beating us and say nice things. It's important the club bounces back."
The Latics had given themselves a chance of survival with victory at West Brom on May 4 but a sloppy defensive display three days later allowed Swansea to twice come from behind to beat them at the DW Stadium.
A sensational FA Cup triumph over Manchester City at the weekend will be some consolation but relegation left a distraught Martinez reflecting on injuries to defenders ruining their efforts in recent months.
Jewell admitted it was a "valid point", but added that having conceded 71 goals during the season - the worst in the Premier League - told its own story.
"You look at the back-line and there are international players at the back who have defended horrendously," Jewell said. "You could see that against Arsenal on Tuesday night and especially against Swansea last week.
"They came out after half-time against the Gunners and were far the better team and they produced chances. But it's that result at home to Swansea that condemned them."