Relationship with teacher, help please:(?

before any of you say this is lies its not im using a fake account etc to ask this question, basicly im sixteen now but this happend when i was fifteen, my english teacher had always favoured me always told me i was a beauty etc, i just thought he was being friendly. anyway one day i stayed behind to finish of some coursework and he sat down next to me and put his hand on my leg and rubbed it up and down, addmitdly he is very attractive in his late twenties and all the girls like him, anyway he started to tell me how he'd been noticing me and how attractive i was but he wished i was sixteen or eighteen, i sat there and then he started feeling my breasts, i pulled away but he pulled me closer asking if i wanted him, i then began kissing him to then he put my hand on his p en is and then eventually we had sex in his classroom. the next day he put his number into my book (which is only seen by me and him ) and we had a relationship he would take me out (WAAAY OUT OF TOWN) so no on would see, and we would have sex at his flat, it felt special and romantic but now i have left school he keeps asking me to move in. i havent told anyone but my mum is starting to question me having a boyfriend, i dont know what to do :(?