Something I learned from the priest of our church was to write letters to people on sensitive topics. Take your time and do a couple of drafts to get it just right. Give it to them with the caveat of them not responding for a couple of days so they can digest it and fully prepare their response. Then schedule a time to discuss what was said by each side. This will probably take a week to run the course but should be much less confrontational. A really good time to do this is when you aren't going to be around for a while so your S can fully prepare their response.
I started to employ letters when our discussions were becomeing more hostile than productive. I kept thinking "I can't even talk to her anymore". Ah hah, I don't have to, I can e-mail or write a letter. Give it a shot. What do you have to lose? Its not she can't "cut you off" any more than she already has.
FYI, I addressed this issue with my W and it was pretty quiet for a couple of days but then, look out!
Remember to remind your W that you are not a "sex addict", you are just a "man". A "sex addict" would have taken their "show on the road" a long, long time ago. One more thing and then I promise I'll quit. Get to the gym and get buff. If that doesn't work than at least you are ready to "take your show on the road".