Advice pls

Been with my boyfriend a year and all he does is pick me up and then drop me like a sack of shit again. One minute he wants me and then he doesnt, hes fine with me during the day (we are with eachother 24/7 atm as hes off work as his boss is on holiday) and come evening time thats when he will start on me. For some reason i have noticed its always the evening time he will become so rude and nasty to me for no reason. He will argue with me and tell me he wants to leave and doesnt want to be with me anymore! Always throws in my face that he will leave me. Then hours later he will say he does wanna be with me then hes fine until the following evening. Since hes been off work he comes everywhere with me but now he has an appointment in london (its true ive seen it for myself) he wont let me come… i want to leave him because im not happy and all we do is argue but i just cant leave, im struggling so bad to leave. He treats me like utter sh*t every single day and i just cant keep doing this anymore. He is so controlling and all he does is accuse me of cheating. I really want to leave but finding it so so so hard to. Keeps telling me when i go out he will leave and that he can do so much better than me. All ive done is be nice to him and i get treated like this