Terrified of living with ADHD spouse again - how do we move forward?

Hello my lovely people! 

I really need some advice on if there's anything I can do to chat to my boyfriend without offending him, and move forward, so we can possibly live together again.
A few months ago my boyfriend told me he thinks he still has ADHD after being diagnosed as a kid, and we both agreed it fit a lot with how he is. To be honest, it's been a shock to me after being together four years - I feel like I'm with a new person, and I feel sad that it's never going to get easier - I always thought he was messy and lacking attention for certain things due to age, job and environment.

I've tried reading up about it a lot, and tried to talk to him about it. He has no interest in medication or counseling. His mum tried all sorts of methods with him as a child and none of it worked, while ritalin made him lose all his friends and he still ended up failing essays due to his dysfunctional family life. He has told me I should take him or leave it - this is how he is, it isn't a condition but his personality. He said if he doesn't make me happy why am I staying with him? He laughed at me for reading a book about it, and told me he was unique - no book will tell me what to do and I should talk to him about it, which I have been trying. 

He has limited interest in a good diet and exercise, going for the easiest, tastiest options first, with little routine on when he eats, and it's beginning to show. I know diet and exercise is meant to help, and it's really helped me overcome anxiety and feel good about myself, but if I want to spend time with him, I find it hard to keep it up my healthy endeavours. I'm starting to feel extremely pissed off that it's so difficult for him to do basic things such as brushing his teeth, putting his clothes in a chest of drawers, cooking, turning lights off, showering, and that it's unlikely to change after how our initial chats have gone. I understand that these things can be difficult but in my head I feel these basic self care things could really help other areas in his life - but I don't know if that's just from my own, non ADHD experience. He says he tries to eat healthily and I end up being critical as he's eaten bacon, two pies and fried chicken, which I doubt helps anything in hindsight.

 I feel all critical and annoyed that he doesn't seem to want to make any positive changes, and I hate feeling like this! What happened to the fun loving times!? 

We have lived together in the past but I'm wondering now if it's ever going to be possible again. When we lived together last time it took everything out of me. We have discussed having separate rooms, as I feel like I need a lot of alone time to make sure I don't lose sight of myself. I am generally feeling terrified still however, as I feel there is no progress and it will end up how it was before, and if that's the case, how can we grow up to have kids and buy a house?! 

How have you guys with SO's overcome the problems you can face as a result of ADHD? Is it possible to talk about it without offending one another? He's such a lovely, funny and kind guy, a best friend, but I also am starting to wonder if we have a future without dysfunction and chaos. I really appreciate it if you've managed to read this far and any advice you have. X