Ultimately it's up to you, but as a male I can tell you that porn use is the norm, not the exception. Though I don't have a partner, I recently made the decision to quit porn for good after realising I've used it at least once a week since turning twelve, and it's definitely had an unhealthy impact on my psychology. I don't think I'm abnormal either, at least not for my generation.
The fact your partner has come to you, confessing and wanting to change, is probably bigger than you realise. The fact that he himself recognises it as a problem is huge. Imagine if you had have caught him viewing porn, and he had to find out through you that it wasn't acceptable, and it was only due to your insistence that he quit, could you ever be secure in that relationship again, knowing that the only reason he holds those values is because of your insistence?
I know it's gross, and if you really can't handle it it's really up to you how things proceed. But my big thing is managing expectations, and there's an important question you need to ask yourself: Is the fact he had a porn addiction worth being alone for? I'm saying there's a significant likelihood that subsequent relationships with men will be with men who either have used, or used porn. So if that's your standard, that's fine, but you should know what it means to hold to such a standard.
I hope everything works out for you regardless.
