When will I learn?

When will I learn to listen to my body and ease back/stop the training if I am sick???  I think we are all beginning to work out the answer to this.... NEVER...
I have no idea what to do next, when to start back, how much to do, how little to do or even where to start.  After 2 weeks off training, 1 of these I was literally unable to get out of bed.  This week was supposed to be my 'recovery' week but as I reach Sunday evening, a deep sinking feeling hits me.  I am STILL not right.
To cut a long story short, I got sick almost a month ago with a cold but pushed through with a quiet training week that week, just doing bits and pieces but not pushing myself too much.  I didn't get back to 100% before pushing myself thought the 'Tough Guy/Girl challenge' and then it was all over.  It was all downhill from there.  I actually ended up with the nasty flu virus that has been circulating and just to top it off, a nasty D&V bug for good measure. It was an 'interesting' week!
 I don't think I have ever been hit with a flu this nasty in my life.  It completely wiped me of every ounce of energy and I thought at one stage, I was actually going to end up in hospital. Believe me, I'm a tough old bugger and can generally push myself though any pain barrier in my way.  I have given birth 3 times, broken bones on countless occasions and had my fair share of knocks over the years!
I am now left wondering - with 15 weeks left to go until I am meant to be doing my first ever half ironman, where on the earth do I start?  The Rotorua Ironman is a particularly gruelling event as it is.  How on the earth am I going to get my strength back to where I was a month ago to continue on my merry way.
I know, 1 step, 1 day, 1 week, 1 month at a time.  But where do I start??