Jill Biden addresses the audience at Sixth & I Historic Synagogue on May 14. (Ari Strauss)

By now, everyone knows how Jill Biden fell in love with a dashing young senator and his two young sons, became a passionate advocate for community colleges and military families and served as second lady for eight years. So there was lots of love but not many surprises at Tuesday’s conversation about her new autobiography, “Where the Light Enters,” hosted by Politics and Prose.

Okay, one big surprise: The audience of mostly women at Sixth & I Synagogue went nuts when Jill Biden walked in — followed by her husband, presidential candidate Joe Biden, and their daughter Ashley. The show of support fit nicely into what the author calls the family’s “circle of loyalty” — an unwavering dedication to each other that transcends everything else.

Jill Biden, a natural introvert, told actress and interviewer Tracy Pollan she has always been private and “scared to death” about public speaking. But she pulled back the curtain a bit on Tuesday.

Like so many mothers, she and her stubborn teenage daughter fought constantly. “During Ashley’s teenage years, I kept a pair of running shoes by the front door. Whenever she and I would get into an argument, I’d put on those shoes and go running to calm down. We argued so much I became a marathon runner.”

She also divulged she learned Barack Obama had asked her husband to be his vice president when Joe took her to the dentist for a root canal. “I was so excited but I couldn’t smile because of the Novocain … One phone call and, boy, our lives completely changed.”

But Biden disclosed some harder truths, like that she expected their oldest son, Beau, would beat the aggressive brain cancer that killed him in 2015: “I believed so strongly that Beau was going to live. They said only one percent [of patients] with glioblastoma will live, but I felt Beau was so special he was going to be that one percent. I just felt that in my heart. And then when he died — and I had prayed so hard that he would live — I backed away from my faith because I couldn’t get over it.”

Despite decades in the public eye, Biden says she still has to cope with the loss of privacy that comes with her life. “When I go to the supermarket, I can see people looking in my cart,” she said. “So I have to be careful what I buy and when. I send my sister to Costco to pick up the personal items.”

And in case you’re wondering? Yes, of course, Joe chimed in from his front seat, encouraging his wife to tell more stories and telling the crowd at the end: “My daughter turned to me and said, ‘Dad, you should come to more of these. It’s the only time mom says really nice things about you.’”