Urgent in need of lawyer's advice or someone who knows rental's rights in Barcelona

Hi there w/o extending too much, I have decided to leave my room (which am subletting w/o a contract) I know mistake number one, for several legit reasons, I informed the guy am subletting of this today and he flat out told me he is keeping the deposit. I offered to look for the person myself; n said that if in case I don't find anyone I could see him keeping half but not all of it.

I can give u some info and the email correspondence I do have, any law experts out there that can shed some light on my problem?

I will be forever grateful !!!!!