I'm not sure there's any way to describe Dear Evan Hansen that's not revolting or overly informative, or both. But I'll say you should go, and then see what I come up with.
You should go see Ben Platt, who'll rightly be the subject of much talk come Tony time. You should go because it's the rare wholly original musical, not based on any previously existing anything. And because Benj Pasek and Justin Paul, A Christmas Story aside (and, to be fair, my horror at that was somewhat unique and not a result of lack of talent on their part), seem to be the real deal as writers of musical theatre. They've made a show that addresses the modern world, for good and bad, and finds uplift both in the story's spinning out of control and in picking up the pieces after it falls.
There's some kinship with Next to Normal, which I hated (a lot), probably from the directorial hand of Michael Greif, but mainly as a flavor, a small-cast musical that's a family story. The first act feels like a whole story by itself; the second act manages the "and All That Followed" far better than the last tenant of The Music Box (Shuffle Along), and makes the whole thing a different story than it appears. After building a viral/"It Gets Better" sort of vibe—and managing to sustain both the message it creates and an indictment of social media culture—it finds a shattering, multifaceted climax and reassembles the pieces again. By rights it should be grim or treacly; somehow it's neither.
And so you should go because you can probably use a bit of bucking up, even if you don't know it. It could cut a bit close to the bone, but art does that sometimes. If you let it, it'll patch you up afterward.