The Cardiff Blues flyer was selected to face England in the Championship's curtain raiser but broke down with an ankle injury just days before the big kick-off.
While an ankle also ruled Halfpenny out of Wales' autumn series, the latest set-back was a stark reminder of the heartbreak suffered on the Lions tour of South Africa.
After being named in the Lions squad in April, it was announced that a thigh injury would rule Halfpenny out of the beginning of the tour.
He returned to action and linked up with the Lions mid-way through the trip but withdrew with a reoccurrence of the problem after just one game.
"I broke down in tears because I was absolutely devastated to be ruled out of the England game," said Halfpenny.
"I had put in all that hard work to get back from the first injury. I was happy with my form after a couple of Man of Match performances for the Blues and was named in the team to play England, only for it to happen again. I was gutted.
"The pain was immediate and I feared the worst but thankfully it was not as bad as I thought.
"I guess I've been unfortunate with the timing of my injuries. It was similar to the quad injury before the Lions. I managed to recover enough to get back but then it went again.
"I was gutted to miss the first few games of the Six Nations. Watching from the stand is very frustrating when you would love to be on the pitch. But I'm relieved it's not all over for me, I can still make a mark."
Halfpenny missed the victory over Scotland and had to contend with being an unused replacement against Italy.
But after producing a Man Of The Match performance in the Blues' 16-11 victory over Edinburgh Halfpenny has declared he is ready to take on the Irish.
"I was really pleased with the way the game went for me and with how the ankle felt," added the 22-year-old.
"It was a real test of the injury and I came through without any problems. I spent the time out training hard, I've put on weight while losing body fat so I feel sharp
"Morgan Stoddart has the Welsh jersey and has been scoring tries so it's up to me to convince the coach to change things. All I can do is play as well as I can."
Halfpenny will come up against some old friends on Saturday and he has revealed Wales are ready to let loose.
"We were gutted after losing to England but the boys showed a lot of character in Scotland and proved a lot of people wrong. That's where the confidence came from to win in Italy and now there's a real edge and a buzz to the squad.
"Our defence has been pretty good so there's a lot more emphasis on our attack this week. We have the players who can create things and show some magic.
"There's plenty of rivalry between the Welsh and Irish lads through the Magners League as well as in the Six Nations but we all got on really well, both on and off the pitch, during the Lions.
"It was great to meet some of the guys I had looked up to for years, guys like Brian O'Driscoll and Ronan O'Gara, and to learn from them.
"Me and Keith Earls also got on well because we were sharing the duties of carrying Leo the Lion as the youngest members of the squad.
"I love that part of rugby, playing against players on the pitch and then enjoying their company off it.
"But we lost to Ireland last year and were well beaten on the day. It was pretty tough after the game, everyone was devastated.
"It was one of the most disappointing performances we've had in recent years so we want to put that right. We don't want to feel like that again."