First remember that this is not a judgement of your personal worth.
The first job now is to find out why if you can. Maybe the why will help you land work with them in the future since you won’t make the same mistake. Maybe you’ll find out that you were really just a price check and need to revamp your client vetting process.
Maybe like a few of mine you’ll find out that despite your discussions the value wasn’t there in the project and it’s time to learn to have better discussions around value and be comfortable using hard numbers in dollar conversations.