Berserking
I'm not sure how helpful it is for me to answer this, because I have a curse called bipolar disorder. It essentially forces me to go from the lowest of lows to the highest of highs without much caring how I feel about it.
That's not to say people with bipolar disorder can't also face suicidal depression, or are not at risk for it; it's a spectrum, like anything, and everyone's experience is different. But in my experience, if I allow my brain to stay at depression levels too long it'll get sick of my shit and say "Hey, time for something different" - then I'll flip into what they term a "manic episode", where I will literally feel like a god and make horribly irresponsible decisions until I'm sedated and my brain chemistry resets.
I've only hit this point in my life once (thank god), and it taught me two things: 1) I have some killer self-preservation programming, and that's okay 2) When I don't take care of myself, other people suffer for it.
The second of those realizations is what spurred me to get myself back together. My family has tried their whole lives to raise me to be happy and healthy. I have parents, siblings, a partner, and friends who really care about me. It's not about the numbers of them, because honestly it only takes a handful; but when I think about how my actions impact them - or how awful it would be if I did something stupid and got myself killed - then I realize that my existence isn't just my own.
I am a supporting character in other people's lives. I provide laughter, comfort, and comraderie. I don't have much choice in my role, but as a berserker I won't go down easy; it'll take a lot piled on to bring me to my knees. That also means I can take on more when needed. If my friends need someone to dump / vent to, I can handle it. When life gets shitty and those I love need help, I won't give up. I can be the person others can depend on because I literally can't quit, I can only go insane (for better or worse).
That said, my weakness is that I can't transfer this curse to anyone else. It's not like I can bite somebody and turn them into some biochemically-induced emotional barbarian. I've had several loved ones suffer from suicidal depression; I've nearly lost some, and lost at least one. It is heart wrenching. No matter how hard I try, or even literally beg, it feels like I can't help or do anything to make it better.
I've had to accept over the years that no matter how much I try, it's up to people to find their own will to go on. They have to find the spark inside themselves; I can't force them. It makes me feel hollow, like a revenant doomed to watch those around them fall while fighting alone in the darkness, until something finally takes me down.
If I could give any advice, it would be to look to your adventuring party. You may not think you have one, but you do. There will always be someone whose life is brighter with you in it. Life is a co-operative game; we all play it together. When you need support reach out to them - don't let them lose you without a fight.
Because it's lonely fighting on in the darkness.
And your light is not something that can ever be replaced.