You need to decide, with your big head, what you want. Is it a divorce, uncomplicated sex, a relationship with the girl, or to fix your marriage?
Sure, it's tempting to have an affair, but you know that is not fair to your current wife. Yes, it's wrong of her to deny you sex, but you have to accept some of the responsibility here, you have allowed the situation to go on. Have you treated her well, been romantic, tried to satisfy her sexual needs? Have you told her this is important to you? Gotten counseling? You do not have to accept a sexless marriage, but it will take work to resolve this.
If you want out of the marriage, man up and end it, then you can pursue this new relationship with the girl without cheating. It may or may not work out, you have no way of knowing, so you could end up single, that is the risk you take. Women who throw themselves at married men tend to have baggage, or emotional issues, which you don't see because you have the hots for her.
Do you just want uncomplicated sex? Well, no one is stopping you, but you know that is not the honorable thing to do. Are you willing to live with the guilt? What if your wife finds out, are you OK with the possible consequences? What if your lover gets pregnant? Has a VD? Contacts your wife or the elders and tells all? Is a momentary fling worth that risk?
...OUTLAW