Hi Ian,
I know after a long time of not eating food which you may consider high in fat can be terrifying..
But i think you need to start introducing them in slowly... Some foods contain fats which are essential to be healthy!
Maybe just start of by having one thing a week and slowly slowly increase what you have
But remember sugars and fats are essential in EVERYONES diet.
We need a balanced diet to be perfectly healthy
If you find it too hard try writing down why you should eat it. Then you have to write just as many reasons as too why you don't want to eat it.
Good luck