What did I just do...

A little history and I'll try and keep it as short as I can and I'm really sorry for any mistakes.I am 20 year old f and my bf is also 20 years old, known him since primary school, been together 11 months.We were great at the start and we are great alot of the time.I suffer from depression and paranoia so I accused him a lot ( on meds etc) Things had got better since I got help and my anxiety dropped and so did my accusations so everything was good.Still had the odd attack of paranoia don't get me wrong but on the whole everything was better until my boyfriend changed his behavior.He would tell me he wanted to cheat on me to hurt me,make fun of the fact that I had no dad in the picture when I was growing up, tell me I was insane and that he would leave me because no guy would put up with me, tell me I was poor and not good enough but the worst thing was when he would tell me often that he wishes he was like my ex who I was with for 3 years ( stupidly) who beat me up , who I ended up in court with by the end cause he attacked me in front of my mum when i left him and hit her aswell.He tells me he wants to hurt me like my ex done to me , put me through hell and make me suffer.He scares me when he says this, I tell him to stop but he doesn't he thinks it's funny.I ended up slapping him for saying it to me and refusing to leave my house when he was drunk ,he said I was just like my ex because I hit him and in a way I know he's right but today was something else I was my ex.

He arranged to meet me in town for a certain time was nearly 2 hours late because he decided he wanted to go for lunch with some people he just ran into , I was upset because I still suffer anxiety in big places ,I waited in the train station for him , I told him I was upset but he said he was sorry and I tried to forget it , we went on about our day and when we got back to his I told his brother , his brother said he was out of line , so I asked him why didn't he return my calls.He told me '' It's rude to call people infront of your friends when there talking '' I replied so it's not rude to leave your gf for 2 hours waiting .. He laughed and told me to get out of his house and I was a ''fucking retard'' I got so angry I cried and he was laughing as usuall I pushed him as I stood up and he stumbled and I tried to knee him in the leg or the side missed and ended up hitting his face and braking his nose , I was so shocked by what I done i grabbed my bag and ran out crying I didn't even look back, I was sick outside and still so shocked.I've never made anyone bleed or hurt before I don't know what I've done , I don't know why , I seriously don't understand why this happened ,I came running home and told my mum and that , It's been 7 hours since it happened and I still can't stop crying.My boyfriend seems to think it's funny and saying it's okay but it's not , How do I make sure I end this , for his sake aswell as my own , I love him and he still wants contact and in a way I do to but I can't stand what I done to him, I'm just as sick as my ex, I didn't come here for sympathy , just on tips on how to end a relationship , Since I already told him I was ending it and he told me he wouldn't let me do it. He lives round the road from me , How do you split up with someone you love but know you can't be with for both your sakes?. I'm sorry if this is full of mistakes just heads in a complete mess.Honestly can't believe I hit someone nevermind actually hurt them.