simon - I've just read this thread - I think you've been incredibly courageous admitting all this to strangers - your "plight" (and that of your wife) seems intolerable to me. Can I say:
You need to decide what you want out of life - do you want what could be potentially years of, to all intents and purposes, loveless marriage? If you're happy with that (you don't sound like you are) then do nothing.
If you're not happy with that then you need to take risks, including the risk of your marriage failing.
At the moment you are not getting through to your wife - her refusal to talk is the main issue. If you can get her to talk you may be able to start resolving some of the issues. If she won't talk then you may as well leave the relationship now. You should tell her this "there is no point staying together if we cannot try to resolve some of our issues". (Have you broken down and cried in front of her - does she realise how much you are hurting?) If she won't talk suggest a trial separation, maybe a week or so, until she is ready to talk.
Counselling has been suggested - together or both separately - she may feel able to talk through an intermediary as it were without you there. Do you know any friends or relatives well enough to talk with them?
Obviously top of your agenda is sex but, as many others have said, this is probably merely a symptom of some deeper problem. You mention lack of time and other commitments. My husband works 12 hours a day and a fair amount at the weekend. In addition we both have other commmitments. But it doesn't stop us having time for each other and it doesn't have to for you either if you don't want it to. Your problems sound deeper than this. I don't think you are going to get any improvement unless you are prepared to take some risks.
One final thing - does your wife have bereavement issues she is/has been coming to terms with?. These can take a very long time to "resolve".
Good luck simon - I hope you start getting some answers soon.