Ex wants to hook up

Hey guys this is my first time posting on this but i dont know what to do, so i had a crush on this guy but turns out he does not like me back and so out of no where my ex texts me and asks me too hook up w him. Thing is a virgin and last time i hung out w him i only gave him head and he wants to have sex and i think im ready but im just nervous and over think everything, what should i do?!?!?