Pete Alonso and his bat reached their breaking points Friday.

After a foul out with a runner in scoring position, the Mets first baseman snapped his bat over his knee like a twig.

Following the series-opening loss, Alonso said he has “played really bad” and was as frustrated as he ever has been in a five-year career.

So the news Buck Showalter delivered to Alonso in the manager’s office Sunday might have provided some perspective: He is an All-Star for a third time.

“I hate to see good people and a good player beat themselves up,” Showalter said before Alonso played a big part in the Mets’ 8-4 victory over the Giants at Citi Field. “But I think it’s good timing for him to be reminded how good a player he is.”

Alonso became the sole Mets representative when rosters were unveiled and joined Keith Hernandez as the only Mets first basemen to be named to three All-Star teams.

The 28-year-old’s competition made the honor especially significant: First base in the National League might be the strongest subset of players in the sport.

Alonso, Freddie Freeman and Matt Olson all were chosen, while Paul Goldschmidt became the odd slugger out.

“We have some pretty marquee guys at the first-base position,” said Alonso, who also was named an All-Star in 2019 and ’22. “It’s really awesome. It’s a super-high honor, and I’m excited to represent the Mets in Seattle.”

He will be representing the Mets in the Home Run Derby, too. Alonso, a two-time champion, announced he would participate in the competition for a fourth time, this time turning to childhood coach Mike Friedline as his pitcher.

As if warming up for the event, Alonso socked his 25th home run of the season, a no-doubter off Ryan Walker, to pad the Mets’ lead in the eighth inning.

It was Alonso’s first dinger since June 25, and he entered play in a 2-for-20 slump in the past week.

Showalter has noticed how much the recent downturn has weighed on Alonso.

“He takes on the responsibility of how much his teammates and his team depends on him,” Showalter said of Alonso, who finished 2-for-4 with a bases-loaded walk and three RBIs. “It’s hard doing the things that he spoils us with.”

Alonso pulled into third in the majors in home runs despite missing eight games in June after he suffered a bone bruise and sprain in his left wrist.

Showalter argued Alonso has been “one of the league leaders in unluckiness,” and the advanced statistics back up his theory.

Alonso entered play with a .217 batting average, but a .266 expected batting average.

Hard-hit balls have become outs, and maybe his seventh-inning double — which just escaped the infield and went down the first-base line — bodes well.

It is possible he recently has brought some frustration to the field and made errors Friday and Saturday.

Former teammate J.D. Davis reached base twice Saturday and said he tried to talk to his pal, but Alonso “was very mumble-mouthed.”

“Pete sounded like he was … not Pete-like,” Davis said. “Pete is a very jubilant and joyful guy in the clubhouse, guy on the field, great to play with. Even as a guy who played with him for four years and had a 30-second conversation, have the sense that he wasn’t himself.

“It’s definitely different, and it takes a toll on you, especially when there are such high expectations for that team.”

Amid a dark first half, Alonso’s power has been a bright light.

— Additional reporting by Ryan Dunleavy