The short of it: Your character needs a way to find hope.
As others have said, you can skim over the entire process and let readers assume that your character’s figuring things out. But in my opinion, if the trauma was a major driver of your plot, so should your character’s recovery.
I have a fairly extensive background in dealing with mental illness, and there is one recurring pattern. People who suffer from (major) depression often use phrases such as, “What’s the point?” because they have lost all hope for the future.
At some point (through therapy, or otherwise), they find someone (or something) they can relate to who has endured the same struggle, but who has already progressed past that obstacle (without necessarily being “cured”). This shows them that they are not alone in this struggle, and that yes, those hardships can be overcome.
This is one reason group therapy and support groups are so powerful for survivors of trauma.
But just as when trying to help a depressed friend, the last thing you want to write is on-the-nose dialogue where some know-it-all serves the main character with a solution on a silver platter. “You MUST do this if you’re going to get better,” or “Look at all the people who have it worse than you.” And magically, your main character sees the light, bounces back up, and all is well.
More people than you think suffer from mental illness. I can guarantee you, reading such dialogue is going to piss them off. That’s not how things work in the real world. The answer must feel self-generated. So your character needs to undergo the same process.
Have various secondary characters, or mere circumstance, (inconspicuously) present them with clues. Then let your protagonist figure it out on their own.
In the novel I’m writing, I put my protagonist through such an ordeal, by making her lose everything. I follow up with one single nihilistic chapter, but pretty quickly her best friend comes to the rescue (you don't want to bash your reader over the head with how desperate your character is getting, because reading that sort of thing gets old quickly).
As I mentioned earlier, the best friend doesn’t offer solutions, only support. Just like in the real world, the first thing you offer is support, not solutions.
Of course, depression isn't cured overnight. So she starts to bounce back, then crashes again. What the friend’s intervention did accomplish however, was getting the protagonist out of her inertia.
Support is what gives us the strength to get back on our feet.
She decides to return to the town where she lost everything, in hopes of figuring things out. There, she bumps into a guy she despises, but because he’s trying to apologize for his behavior leading up to her traumatic event, she listens to what he has to say.
Somehow, HE went from being a deadbeat to someone who now has a firm grip on his own life. She determines that the reason he used to be such a jerk was he went through trauma of his own for years. Then the event that caused HER trauma was apparently a wakeup call for HIM. In a roundabout way, she recognizes a bit of herself in him. She realizes they’re rather similar, except he has now progressed beyond that stage of his life, even though no one ever expected him to.
Relating to his struggle is what gives her hope and ultimately sets her on the path to recovery.
This is a major theme of my novel, so I devote several chapters to it. Since this subplot isn’t central to your story, obviously you’ll need to adjust.
Either way, I think it is important to depict the ups and downs of the healing process, because that is what real people with depression experience every day.
I imagine your character will go on with their life, with that trauma constantly in the back of their mind. It might impede everything else they do, but little by little, clues will show up in everyday events that help them connect the dots.
Hope is what allows us to move forward in the face of overwhelming odds.