What should i do, i think my relationship is going no-where?

i have been with my fiancee for 10 years now nmearly 11. After our first year together he started hitting me and calling me names, even when i was pregnant with our first child. I decided to stay around and see if having the baby would help our relationship. It didnt if anything it got worse and i decided to call it off, which after a couple of weeks he talked me into taking him back and we then got engaged. After a few months i was pregnant again and the it still continued. i know ur probably wondering why i put up with it, but i was in love with him and we had some good times together that i hold onto.After a while my step-dad told him that if he didnt stop he would basically give him a flogging. It worked as he stopped for a few years and we had our third child, by that stage i had been through so much emotional and physical abuse that my feelings were no exsistant. I then decided to end the relationship again. After 2 months apart and having him call every day saying he would change i decided to work things out for our kids sake and i knew i did still love him deep down. Probably the worst mistake ever! the physical abuse was something that happened maybe once or twice a year but the emotionl was all the time tho at the time i didnt realise it. So after a couple of years i decided enough was enough it was affecting me and the kids and called it off again. We were not together for 6 months that time and in that time i started seeing another guy which the relationship failed, but as usual he was hounding me and he would turn up and cry, bringing me flowers and stuiff like that. Making promises and telling me how much he loved me, so stupid me took him back yet again. I know its probably one big headache! well these days he throws stuff at me, he's hit me once after i came home from a night out with friends, he always says im cheating on him because i dont want , he snoops in my phone, he's always wanting detailed answers about what im doing and where ive been. He doesnt like me going out to see friends whilst he is at work, even going to the gym has a sinister reason for him. He says im stupid, makes me feel badly bout the way i dress as he hates all my clothes, he gets grumpy at me all the time basically and when i say no to he starts getting really irate saying im getting it elsewhere and then tells me he might do the same. But we do have good days where everything is perfect and i find if i stay home and do wha he likes me to do the only problem we encounter is the problem. I dunno why i dont want , i just cant b bothered really. we r meant to get married this year and im just scared that maybe im making a wrong decsion or if im blowing things out of proportion. I know i aint perfect, but i trust him and i dont carry on at all if he goes out with friends, like he does to me always saying ill meet a younger guy better than him, or he will make little mouth signals and sounds when i talk about how excited i am as i dont get out much at all these days, even to catch up with friends for coffee. Please help me :-/