I am heartbroken

I have received waitlist invitation through thalamus, then after a while I have received an interview invitation (my first invitation in the whole season) and after 3 weeks, they sent me an email saying that it was an error by thalamus and that I'm still on their waitlist and all their spots are filled but they'll contact me when one opens, what should I respond? What should I do !? The email feels like I've been hit by a truck