I'm glad to see you being encouraging to someone but do you really believe sexual confidence is EVERYTHING in a marriage...like you stated? If you do, and you weren't just blowing that out of proportion in your post....you might want to examine this, because this could be YOUR hangup. Sexual confidence is a component in a good marriage (I believe so anyway)....but it is most certainly not EVERYTHING, there are many, many, many other things that are also very important (some in my view equally important)....Trust, respect, friendship, communication....just to name a few...I could go on.
I'm not blasting you here....just pointing out that "IF" you really do believe what you stated....then THAT could be your biggest issue, because I feel I can pretty much guarantee you....your W doesn't see it that way. And while I believe many people on this board would agree sexual confidence is nice and quite appealing....it's not EVERYTHING in a marriage.
Seriously, take some time and thinkg about this. If this is truly your belief, you are going to be your own roadblock.