The on-loan Manchester City player was lucky to escape uninjured after Rangers midfielder Halliday launched himself at his opponent just three minutes into Sunday’s William Hill Scottish Cup semi-final at Hampden.
Referee Willie Collum showed Halliday mercy by only producing a yellow card but he could have had no complaints had it been red.
And Roberts confessed he was just glad he was able to walk away from the horror challenge.
Asked if he felt Halliday should have been dismissed, Roberts replied: “Looking back, Scott Brown did [a similar tackle against Ross County last week and was sent off] but I don’t know.
“It was a bad tackle. I’ve seen it back again and it was a terrible tackle.
“I’m just thankful I didn’t get hurt.”
Having survived that early scare Roberts went on to play a crucial role in the Hoops’ 2-0 win, which booked them a May 27 final with Aberdeen.
It was the 20-year-old’s pass which sent Leigh Griffiths scampering into the box as he won a second-half penalty. Scott Sinclair tucked away the spot-kick to add to Callum McGregor’s 11th-minute opener.
It was a demoralising afternoon for Rangers, who have now lost four of their five Old Firm encounters this term to Brendan Rodgers’ undefeated side.
Rangers could have had no arguments if Tom Rogic had found the net in stoppage time rather than slamming the ball off the base of Wes Foderingham’s post, such was the grip the Parkhead men had on proceedings as they chase down the treble.
But the victory had all the more meaning for Roberts 12 months on from losing to the Ibrox club at the same stage of last year’s tournament.
His empty-net miss cost Celtic dear as Rangers went on to win on penalties but Roberts feels he has now had the last laugh.
“There’s always talk in the media [about the gulf between the two sides] but I thought we showed a real domination on Sunday,” he said.
“That’s the way we’ve been playing all year, no matter who we’ve been up against.
“In Old Firm games, form goes out the window but we’ve forgot about them and played our own game. With the ability in our side we’re always going to create chances and finish them off.
“It was a real low last year, especially with me missing that chance and us going on to lose the game.
“But we picked ourselves up and this year we’ve been phenomenal. To top it all off with a Scottish Cup win would be brilliant, so we’re looking forward to the final.
“We had a clear mind this time about winning Sunday’s game. We began the week confidently and all memories of last year went out the window.
“We went into the game strong and confident and dominated the game from the start.”
Roberts is now just four weeks away from completing his 18-month loan spell from City.
Whether he has what it takes to break into Pep Guardiola’s star-studded line-up remains to be seen but he preferred to play it coy when quizzed about the possibility of spending another season north of the border.
The England Under-20 international said: “I don’t know what’s happening next year. Hopefully we can win the Scottish Cup and I’ll finish the season on a high.
“But after that, we’ll have to see. I’ll just take each game as it comes and when it comes to make a decision on my future, I’ll make that call then.
“Obviously it’s been brilliant being here at Celtic and I’ve enjoyed my time here.
“Everyone knows I love the club and love playing for them but who knows what can happen in football.
“But if I am to leave, a treble would be the perfect way to sign off. As a group we’ve been brilliant this season.
“The last game against Aberdeen will now be crucial and if we could win, it would top off a great campaign.
“Hopefully we can do that. We’ve definitely got the ability.”