I think you really need to ask yourself "WHY" you want your wife back. Then you need to think really hard about whether if you were to express the reason "WHY" in the form of a statement to your wife it would have any effect on her decision to leave you. My H found himself in your exact situation not too many weeks ago (though this might not be totally true since there were issues in my marriage beyond the sexual disparity and my H was pretty disrespectful towards me about the sexual issues etc. so grain of salt, your sich might be more hopeful than mine) so I can tell you exactly what you shouldn't say/convey.
1) Do not convey anything that would tend to make your wife feel sorry for you because you are now so miserable without her. Her inclination will be to see your tendency to feel sorry for yourself as the root of the problem and won't be impressed by a change in context. So anything conveyed along this line will just make her feel like you are clueless.
2) Do not convey anything that would give the impression that you have now magically figured out what "she" or even the two of you together might do to improve things in the future. An angry "Too little too late" will be her reaction.
What you should do is anything that you might rationally do to prepare yourself to be ready to date or have sex with women other than your wife. When you can look at yourself in the mirror and say "I have a lot to offer in a relationship both sexually and otherwise." and stop making excuses or feeling sorry for yourself then you will be on the right track.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver
