As I see it... and trying not to be biased here...
Most men do use porn, whether they are honest about it or not
Some men have a big issue with it - whether he was addicted is debatable. Is it addictive or is that common parlance now for "enjoyed it often" and sometimes "to hell with any consequences of that". Not sure.
Porn has problems in terms of the ethics of some production, issues it causes in relationships, etc. Some see it as fundamentally problematic and degrading etc however it is made, and some don't
Many, but not all, women have an issue with it for personal or political reasons
If there is a mismatch in attitudes to porn it will cause issues in your relationship, unless one of you changes your attitude (unlikely)
He might be being honest and that might be to be commended. He might not be being that honest, you'll never really know
Depends now on how big an issue it is for you
I've dealt with this in previous relationships and am currently in a relationship where my partner claims not to be watching it despite him doing so most of his life. Do I believe him? Not 100%.
I am pretty anti porn. Always have been. But I am also realistic and don't think that every man who watches it is a monster. It's so normalised to them. I think the whole situation now is pretty grim but it is where we are. That's not defeatist, just trying to be more pragmatic in my own response to men. I've had partners who were definitely not watching it, one who lied a lot about it, others I suspect lied a bit about it, this one.... I don't know. I'm tempted to believe he might be trying not to but like yours, might slip up on occasion.
If I was somehow made aware of huge lies and dissonance it could be relationship ending; honesty I do appreciate though.
It's difficult. Feel for you. Just know this is something many women are having to wrangle with one way or another.