My relationship is in trouble?

i am living with my partner for over 12 years. I was 27 yrs old at the time and single and she had two young boys and was seperated. IWe got on very well from the start and i quickly moved into her home with the boys as i had been renting on my own. Anyway 12 yrs later we had two more boys between us they are now aged 9 and 10. The older boys are now 21yrs and 23yrs. The older boys still live with us and i am finding things increasingly difficult as i feel the older boys rule the house and are basically let do what they want. Neither of them work and are hanging aroung the tv day after day after they get up at about midday to 3 pm. Last xmas i lost my cool with the 21yr old and i gave him a piece of my mind and he lashed out with a head and he broke my nose. He is let carry on as normal in the house and ever since i have been increasingly unhappy in this house. I went fo rcouncilling with two diferent councillors and the last councillor told my partner to encourage the 21yr old to move out by 6 months or else i should get out. He never moved out and i am stil here too for the sake of my kids who i love very much. I am not sure if i am in love anymore as i twinge thinking my partner has raised a son that i hate very much. I wish i liked him but i really am unhappy living around him. I have been so depressed in recent months i lie in bed all night unable to sleep. I think if i end the relationship and leave i will then feel even worse. What in the name of God should i do?