I feel your pain buddy, diabetes is an exhausting illness and leaves us at risk of depression.
I've been depressed at several points in my life for extended periods and didn't think anything would help, I sneered and responded negatively when I was offered advice on diet, sleep, exercise, lifestyle changes.
I eventually got completely fed up, I was not having much luck with SSRIs and SSNIs and found the side effects of anti depressants almost as bad as the illness.
I know we're all different and everything is context specific, but here is what worked for me.
1) I stopped obsessing over diabetes, I stopped chasing a HbA1c under 6%, eased off, I still kept doing the right things but the hours a day I spent focusing on my diabetes dropped significantly. Interestingly my HbA1c only went from a 6.1% to a 6.2% despite a massive reduction spent time testing, eating strict no carb etc.
2) Exercise, I started exercising daily, cardio mostly, along with some resistance stuff. I lost 20kg and my energy and well being rocketed. Running, cycling really are good for getting in the zone.
3) Lots and lots of water. I get 3 litres a day, really helped with my well being and energy levels. I read a few books on nutrition, M Pollen, Gary Taubes and have spent the last two years eating lots of greens, lean meats, fish and limiting carbs. I don't eat processed or packaged foods and obviously limit sugar. This again has had a big impact.
4) I also recognised that I was quite an anxious person and would be subject to anxiety cycles that good last for days at a time. I know believe anxiety to be the cause of my depression. I've been attempting to retrain my thought processes, I've pretty much come to the conclusion that all worries are either based in the past or the future, so there is little point expending energy on things beyond your control. I try and be mindful as much as possible, avoid rumination and keep myself busy and in the present.
Any activity which enables flow, e.g. an activity which you love in which you can become completely absorbed is great for mental health I think. Mine are racing around on motorbikes or running!
4) Sleep, I started tracking my sleep duration and insuring I slept between 7-9 hours a night, if I had a deficit at the end of the week, I made it up over the weekend. I appreciate this might not be feasible for everyone due to work and family commitments. But sorting out my sleep cycle, limiting screen time in the evenings, this again paid dividends.
I think small sensible changes such as the above work together in a synergistic fashion and enable you to generally pull yourself up out of the abyss (mild to moderate depression only obviously, I don't want to belittle other peoples struggles)
I don't think being "strong" comes into it, that's typically advice from somebody who has no experience of mental health issues.
Just recognise you're having a tough time, going through the mill and need some time to find your feet and feel well again. It won't last forever!
All the best,