I dumped my man because he has cancer — now I’m running in his honor

She’s putting her heart and sole into this race.

Danielle Epstein, 32, says she is running the London Marathon on Sunday in honor of her ex-boyfriend — after leaving him because his cancer battle was “damaging” her mental health.

Her ex, Jelle Fresen, was diagnosed in September with a rare and aggressive type of brain cancer, a grade 4 medulloblastoma, at the age of 37.

Fresen had to learn how to walk again after 17 hours of brain surgery. He also underwent six weeks of radiation therapy and began nine months of chemotherapy. The struggle was simply too much for Epstein at the time.

“I felt like the most awful person, leaving somebody because they have cancer, but it was damaging my mental health, and it wasn’t helping Jelle,” Epstein explained to South West News Service.

The physics teacher explained she was so “worried” and “devastated” about Fresen that she was having trouble sleeping and eating.

“I was having panic attacks and was on so much medication to sort myself out I just couldn’t function,” she recalled.

“I still love Jelle deeply and want to support him, but I came to realize I couldn’t stay with him as his partner.”

The pair split — and now, Epstein is running the marathon in Fresen’s honor to benefit brain tumor research.

“I felt so helpless watching all this unfold, so I knew I had to do something,” she shared.

The couple was buying a house together when Fresen, a Google software engineer, started to experience dizzy spells and vomiting.

Doctors initially thought he was suffering from an ear infection, but he sought out a private MRI after his vomiting worsened.

The scan found the tumor. Surgery revealed the mass in his brain was indeed cancerous.

It’s a type of cancer that’s most often found in children, according to the Cleveland Clinic.

Epstein said she felt like their whole lives “came out from under” them.

The surgery left Fresen with nerve damage, which resulted in some paralysis on the right side of his face.

He also can’t fully close one eye, and has a squint that gives him double vision.

“We were on a certain path to a certain future, and within one day we knew it wasn’t going to work out like that anymore,” Epstein admitted.

After they broke things off, Epstein moved to Thailand to be with her father.

Now the former couple is trying to work on a friendship.

“I’m not a runner, but Jelle has done marathons before, so I thought it would be a challenge for me and a nice tribute to him, and it felt like something to aim towards,” she confided.

She said training for the London Marathon has been physically and mentally challenging — but it’s nothing compared to what her ex has endured.

“I have the best motivation; if Jelle can go through all of this then I can run a marathon,” Epstein said.

And Fresen will be there Sunday, cheering and supporting his former girlfriend.

He said it’s “incredible” that she is running the 26.2-mile race.

“When she said she was going to do a marathon, I must admit I had my doubts,” he told SWNS. “I think she only did about [3.1 miles] when we were together, and that was with a lot of complaining.”

“I’ve got so much respect for her discipline and perseverance,” he added.

Epstein started a JustGiving page to fundraise for brain tumor research, with the goal of collecting about $12,500.

“While his tumor type is rare, brain cancer is not, with one in three people knowing somebody affected,” Carol Robertson, national events manager for the UK-based charity Brain Tumour Research, told SWNS.

“We’re very grateful to Danielle for taking on this huge challenge to help raise funds for our cause.”