You don’t have to be grateful for a hard change to grow from it.

Nobody is owed your thanks for a hard year. You can take whatever the thing taught you and still wish it had not happened, and those two positions sit together perfectly well. The pressure to feel grateful often comes from other people being uncomfortable with how plainly bad it was.

If something is still raw, you are allowed to say that it was bad and that you learned from it, in that order, with no softening clause at the end. Keep the lesson, and keep the complaint too. You do not have to resolve it on anyone else’s schedule.