The thrilling game was one of the many highlights of the weekend, with Rovers running out 38-24 winners in the end.
“It hurts,” Watts told Love Rugby League.
“You want to play well against your old club, and when you get games stolen off you in the last couple of minutes it’s hard to take.
“But all credit to Hull KR. Obviously going to 12 men doesn’t help, but we’ll take it on the chin.
“That’s two games that they’ve got us now this year.
“We’re halfway through the season now, and we’ve got to start winning games. It’s only going to get tougher.
“That’s got to bring the character we showed today out of us, we need grit and determination.
“All the lads are sulking, but we’ve got to take a lot from that game and kick on for next week.”
Watts believes that Lee Radford‘s men can take many positives from their repsonse to adversity, though.
“We got in a bit of huddle, and said ‘Come on now, or this could end up with us getting beat by 30 or 40 points.’ We stuck in there and gave them a game,” he added
“You could see that Rovers were hurting at times. We just couldn’t get that last-ditch play.
“We either pushed it too far, or came up with an error, which is disappointing.
“But we’ll take a lot from that game. Character-wise, everyone was outstanding.”