A full reply to your post could fill a book, but here are a few comments
You are not alone; neither in being a diabetic, nor in having difficulty dealing with it. Posting your thread on here is a good start, and as an ancient hippy such as myself would say, the first day of the rest of your life.
I'm not an expert, but I would think that 4 years have not been long enough to do any long lasting, serious damage; though I'm willing to be corrected
Join Diabetes UK. they have a good magazine & helpline, and a very good guide for Type 2 diabetics. there may also be a local group in your area
Ask your doctor to see a diabetic Specialist Nurse or similar, and a dietician
No-one has been able to prove a link, but people with diabetes often have problems with depression, anxiety, etc, and your emotional eating & lack of motivation is probably a sign of that. Don't be ashamed or embarrassed to use antidepressants or see a psychiatrist
Get books on diabetes from your library. They will be, surprise, surprise in the health care section. Fashions and attitudes to diabetes change so some of them may not be absolutely up to date but they will all help you to understand the ins & outs, and get you used to the jargon
If you have to go onto insulin, don't panic. Modern microfine needles and insulin pens make it easy & painless. Insulin can give you better control too
Lots of areas have easy walking or fitness schemes. Ask at your GP, sports centre, or community centre
Read through as many of the old posts & threads on this forum as you can manage. Same sort of questions, problems, and advice have been on before
Once you start to change, it has a progressive or rolling effect - the more you do, the more you want to do and are able to do. Getting out and about & meeting people will help your overeating & emotions too
Best of luck Zuludog