This is going to be on the long side, but I can relate so here...we...go...
Yes, I sympathize with your twin flame. It's a real bum-kicker how the world is these days. As someone who suffers from depression, who has been suicidal in the past and is also disenchanted with the world and its problems, I can make some recommendations as to how your twin can cope and even feel a sense of passion and un joie de vivre
I have found that, even through my worst bouts of depression, if I focused on the things I love, things I found beautiful and which were wholesome - I felt hope again (and your twin needs to know, there is always
hope) and was happier.
Your twin must have music he relishes, books he loves reading, films he savors watching, or art he likes to look at. He must have hobbies he can enjoy and getting out in nature is always a good thing. Because of his depression, he may well be apathetic and would rather lie in bed 'doing nothing.' That can be 'okay' sometimes as we all needs to rest, but we who tend to worry and depression can also start to dwell on the bad stuff if we are not distracted.
Of course, he needs your support and that goes without saying. Be there for him, reminding him of all the good things and give him things to look forward to (like seeing you next month or soon thereafter).
Another suggestion I have, is for him to 'take a vacation' from ALL sources of negative media. He needs to 'Drop Out'! I don't even LOOK at headlines anymore - except for the ones of my local paper back home (which about things like how the summer tourism was, how the snow-pack for the winter is coming along and how bear orphaned bear cubs were recently released back into the wild). Your twin might feel like he is in a void current event-wise, but it will do him so much good to just give it a pass for a while. If something earth-shaking happens, then someone in my life tells me about it and I assume it would be the same for him too. My family and friends know I've put an indefinite moratorium on all negativity and they are (mostly) respectful of that.
Also, he needs to raise his vibration. He can do this by applying what I have suggested above. He can also meditate, chant, cite 'violet flame' decrees (so good for depression and these can be researched online) and even taking showers and baths is helpful since water is high in vibration. He must try to avoid negative self-talk and if he must be in contact with negative people, he can not linger around them as much as he can help it. The use of crystal raises one's vibration too and I find rose quartz especially nurturing and amethyst especially calming when I am going through a sad slump. Exercise is good as is doing grounding work like walking barefoot on some grass.
This time of year can be a rough time for those of us who also suffer from SAD (Seasonal Affective Disorder) due to the increased darkness as it affects our moods. For me, it it beyond this time of year - having moved from sunny California to dreary ol' England so I've had to gather things about me to cope and much of that is in this post (it's a good thing I'm resourceful! ;-)). Hopefully, your twin is not in so gloomy a location. ;-) I can identify with him not being happy where he's living. Until he is able to move, he just needs to make the most of it and plan for the future as to where he wants to be (again, so he has something to look forward to).
When you're depressed, you are out of alignment with your true self and acting out of the ego's emotional body (which is where most of our issues lie). If he is not 'feeling good' mentally and emotionally then he is out of alignment.
Has he tried flower essences, or the supplement holy basil (tulsi), St. John's Wort, or SAM-E? Those have helped me a treat at different times in my life.
Sleep, that is also important and he needs to be getting enough because otherwise his serotonin levels will drop which contributes to anxiety and depression. He also needs to be eating healthily and regularly so as to keep an even keel on his blood sugar levels to avoid mood swings.
And yes, he needs to strive to be an ever-burning light as that is needed in this world more than ever.
As his twin, he will come to reflect you as your mirror...So, if you
are in a feeling good, positive way and are loving yourself and holding to the light - he, in turn, will come to benefit from that and later, emulate it.
I hope at least some of this helps him and wish you both the best of luck always.