A 76th-minute drop goal from Thomas Bosc sealed a remarkable comeback for the French club, who have been under pressure of late after a desperate run of form.
That looks as though it has now come to an end, and the Dragons boss was especially delighted with Whitehead's performance after a difficult week for the former Bradford Bull.
"I'm really happy for Elliott in particular, he had a lot of emotion in the build-up to the game. The situation wasn't ideal for him but we all stuck around him as a group and they helped him to perform," Frayssinous said.
"He was looking forward to the game, but he was definitely nervous too, you could tell. We told him to leave the emotion in the dressing room and perform like he has been doing over the last few weeks, because he's been one of our best players.
"You could see his effort though, things like an interception after he's played nearly 80 minutes show how important he is to us."
The Dragons are all but confirmed of a play-off place after the win as they are six points clear of the ninth-placed Bulls with just three games left.
Frayssinous believes the victory could be just the shot in the arm his side need heading into the play-offs, admitting his side have been down on confidence.
He said: "There was a lack of confidence within the squad. I think the performance against Saints and the last few weeks we've been doing alright, but there has definitely been a lack of confidence in the camp.
"Even today we dropped a lot of ball, but you could see that we're sticking together no matter what happens and you could see what it meant to the guys at the end."
As for Bradford, they now must surely win their final three games of the season to stand any chance of making the play-offs.
And head coach Francis Cummins lamented his side's second-half performance that saw the game slip away.
He said: "They started the second half really strong.
"We knew we were going to give away some size to them in the forwards department, but we didn't come and meet them enough like we did in the first half. We invited them to run at us and let them march down the field.
"You can't give a side that much possession. We scrambled really well and we worked really hard, but you can't allow a team like that to have so much ball on their terms, and we need to be able to pass and play. We lost our way in the second half.
"We were already struggling for numbers after losing Heath L'Estrange, and we were clinging on at that point already. We had a chance to finish that game off and kill it but we didn't, we gave them too many chances and too much ball."
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