Ella, who cheated on husband Nathaniel Valentino with Essex boy JJ on the E4 experiment, is said to have skipped the star-studded event after finding out that her ex was attending.
It comes after former glamour model Katie, 45, confirmed her relationship with 31-year-old JJ, as they stepped out arm-in-arm during a romance on a night out in Essex.
A source told The Sun: “Ella was invited to the boxing match on Friday but pulled out last minute after she heard Katie Price and JJ were going.
“Ella’s not seen Katie or her ex since they went official, so decided to skip the event altogether to avoid an awkward run-in.
“All of Ella’s friends were there, so it was a shame that she didn’t come. But she didn’t want to risk bumping into them.
“She’s still hurting, so it’s only fair that she takes some time to process it all before she faces them.”
Ella’s co-stars Jordan Gayle and Paul Liba stepped into the ring on Friday night as they took part in a charity fight.
It is not known if mum-of-five Katie actually attended in the end but her new flame was present as he posted photos and clips from the O2 Arena, while joined by his fellow MAFS co-stars.
Last week, The Sun revealed that Katie was embroiled in a new feud after breaking “girl code – Ella blindsided after she grew close to Katie.
JJ famously ended up with Ella after the pair cheated on their respective partners during the TV show and embarked on a short-lived fling.
A source said: “Ella is fuming and feels really betrayed by Katie for talking to her ex JJ.
“Ella and Katie have become friends over recent months, so it surprised her that Katie would do that.
“She doesn’t have any feelings for JJ, she’s just livid that Katie went behind her back and broke girl code.”
Katie and JJ – real name John Joe – have been getting close for the past couple of weeks.
A source previously told The Sun: “They’ve met a few times and are texting each other constantly. She’s really into him – this is the first man she’s actually been interested in since Carl.”
Katie split for good from on/off fianceé Carl Woods on New Year’s Eve after four years of dating, leaving her single and ready to mingle.