Looking for advice to help someone with addiction

TLDR;; Hi everyone, I know this is a support group for people dealing with masturbation but I'm looking advice for someone else.

My partners of 6 years had an affair with a coworker last year and it uncovered a huge porn addiction. We went to therapy for a few months after the initial been going to therapy in spurts for relationship collapse, I had moved out, few months later moved back, stopped therapy, thought it was getting better, would still fight about his instagram followings and porn, then found a fake account, lied about the account, lied about reaching out to the affair partner, lied again about porn, lied again about trying to check up on affair partner....

Basically I long pattern and I keep getting glimpses of relationship repair and I know this can be a really tough addiction to crack. We've on a no sex no masturbation 90 day challenge currently at 60 days is, I recently found out again he's been at least looking at only fans pages on instagram.

Looking to talk with people from the otherside about how I can support them without overreacting so we can get past this in our relationship for good.

Thanks ❤️