Hi SimpleSimon
Sorry to hear your story, thought i'd chime in with my two cents.
I'm a recovering porn addict, was in a relationship with an amazing woman for six years but I sabotaged it and ran away due to my porn addiction - this was two years ago. I've no excuses, I was lonely and depressed, thought having a girlfriend would fix me, but it didn't.
Honesty is key, once this problem is out in the open it loses strength, it's a good step you've shared your problem with your wife, if she's willing, get her on board with your recovery, and get more supportive people on board as well, be it therapists or close understanding friends. I've opened up to a few mates and it definitely helps. If she's the right one for you she will accept you, warts and all and help you with your recovery.
I've been through this before so I understand the feeling of guilt you must be having.
Understand it is your problem and you are responsible for your actions, but you are not alone, and understand that everyone is addicted to something, be it sex drugs, rock n roll or origami, some addictions can be productive some really aren't.
I found out my porn addiction was masking massive insecurities and anxiety, since quitting for eight days i've become very emotional! If you cry a lot its good right now but you'll hopefully stabilize after a while. A certain song would come on the radio and i'd be a blubbering mess! the slightest thing can trigger it.
Are you using porn to escape reality? are you really happy in the relationship? sex with my ex was rubbish to non-existant, we chatted and got along, but the sex was the elephant in the room, a big horrible sexy elephant...
As the previous guy mentioned, exercise is a great way to release dopamine and make you feel good, so crack on!
I believe the key is to be honest, if you slip up you NEED to tell her, if you feel like slipping up ring her straight away, or a friend, or get in touch, or go for a damn walk, do something to derail the thought pattern you get into. Maybe get an accountability partner, join a support group - this is something i'm thinking of doing, you can find strength through others.
Keeping busy helps, i'm watching a lot of self help vids on Youtube.
Keeping a journal helps a lot, record your thoughts daily, i've got a cool app on my phone for doing so.
Enjoy each day of sobriety, pat yourself on the back each morning. You'll find yourself feeling horny, enjoy that too, means you're a red-blooded alpha male and want to procreate with your lovely wife, but learn when to distract yourself from this feeling before it gets out of hand.
Avoid being lonely, tired, and lacking sleep, being hungover at home alone is VERY dangerous for slipping up, i'm always horny when i'm hungover?
so maybe cut down or stop drinking altogether. A good night's sleep can cure 90% of your problems.
Try to practice mindfulness, become more conscious of yourself and others, if you feel a negative thought, don't try to stop it, but observe it, acknowledge it and try to understand why you thought of it in the first place, this helps for identifying triggering thoughts, and you can maybe find out what triggers to avoid in the future (certain facebook posts and certain youtube vids etc.)
If you absolutely must act out and watch porn, make a point of looking at yourself in the mirror during or after, see yourself for what you are - not pretty is it? it doesn't sound nice but it helped me - I didn't stop immediately, but I found the more I observed myself and practiced mindfulness, the more I recognized PMO as a futile exercise - The last time I PMO'd it was such a rubbish orgasm and I felt so dirty its helped me stay away and stay strong.
Couple therapy, and counselling may help? I don't know where in the world you are, but in the UK there's an organization called Relate which provide counselling and therapy, and also sex therapy for couples. It's not free but apparently very good.
Learn to forgive and love yourself.
Umm what else...
Love many, trust few but always paddle your own canoe
Hope I helped. Good luck brother!