Deathhead moth damaged

So I have no idea who to ask about this and I'm pretty panicked.

My moth fell off of the wall recently and I thought that only a small piece of it broke. Came home today to find this wet patch under it. I have no idea how to fix it or if it's beyond help, but I'm gutted and truly adore this lil guy and if he is going to decay because of this I'll be heartbroken.

Any advice? Or anywhere I could ask?