Being threatened online? What should i do?

[Sophie]

someone help, I don't know what to do. im 20 years old and have been talking, camming to this guy who is 33 years old. I used to be interested in him, we have lots in common did sexual stuff over camera. was all a bit of fun really, we met up had sex and then he made things get serious and I don't want them too. my mum would kill me if she found out and now this guy wont get off my back. when I try end it he threatens me that hes going to send naked photos of me to my workplace to show people what im really like and screw me over. and that he loves me and really wants us to work. he thinks ive cheated on him and that's why he wants to screw me over if I have. he wont let me have a clean get away. Ive tried putting him off me but he knows what im doing and still carries on with the threats. I want him to leave me alone but he keeps blackmailing me. plus I don't want anybody to know this happened so I cant tell anyone!!! I personally think hes groomed me, but can that happen when im age 20? I don't know I just need him to go ive tried everything my mums already suspicious about it but she'd kick off and chuck me out . WHAT DO I DOOOO THIS GUY SCARES ME HE THREATENING ME LOOSING MY JOB
this guy is unemployed does know where I work
I work in a salon so they get emails of customers so they would be noticed
only things is he said his ex got him done by police by saying he was harassing her and he said real story was he caught her cheating on him over phone so he doesn't trust anyone and thinks ive cheated on him, that's why he threatening me cause he thinks ive screwed him over but yet he wants me to stay with him to prove I haven't cheated so he wont send pictures. but I don't want anyone to know whats gone on