Hi blingchick and welcome to the forum, tell your boyfriend that it is quite normal to be confused and overwhelmed by his recent diagnosis, but all will become clear over a period of time, Rome wasn't built in a day, as they say
His bg levels are still very high but he can work on them over the next few weeks and im sure there will be lots of advice offered to you both here.
Firstly as you would expect all sugary things need to be avoided like sweets, cakes and biscuits but that is not the whole picture, carbohydrates cause diabetics blood glucose levels to rise to, so your partner needs to cut down on things like cereals, rice, potatoes and pasta. Some diabetics cut these foods out completely others just cut down the portion sizes they eat, it also helps to choose low GI types of these foods, like wholemeal or wholegrain bread instead of white bread, basmatti rice instead of ordinary long grain rice, wholemeal pasta instead of the usual pasta varieties.
Testing will identify what effects these foods and other carbohydrates have on his blood glucose levels. I would recommend buying some books on diabetes there are many about. Ones that helped me get a grip on things were (in no particular order)
Type 2 Diabetes - The First Year by Gretchen Becker
Type 2 Diabetes - In Adults Of All Ages by Dr Ragnnar Hanes & Dr Charles Fox
Diabetes For Dummies
Blood Sugar 101 - What They Don't Tell You by Jenny Ruhl
There are many others but these are a few that I found particularly helpful, they can all be bought on Amazon.
I would also recommend a copy of the Collins Gem Carb Counter book that will give you a good starting point for what carbs are in what foods.
Hope this is helpful and good luck and try not to worry, it does all fall into place eventually