You have just described my nightmare, yojylloh. I have already had enough of living with my eldest son, who's 18. The thing that keeps me going is knowing he'll be moving out in less than a year... If I thought he might still be around at 35, I couldn't handle it at all.
I understand drifting into that situation: you want the best for them, and it's hard to take action you know will make things difficult...
I think it comes down to a balance of needs. When they're little, your needs come way below theirs - many parents even discount their own needs entirely. That's as it should be when they're children: they can't look after their own needs, and it's a parent's job to do it. :)
But there should be a gradual shift, so that as they get older, they take on more and more responsibility for meeting their own needs, and you are able to give yourself some time and attention. Something has gone wrong here, and you're still stuck in a situation you should have left behind when he was a teenager.
You may have almost forgotten that you even have needs. You need to remind yourself, somehow. You have a right to a life, yojylloh - really you do. You have a right to be safe, feel relaxed, have some fun, live a little!
It isn't going to be easy. It's hard to 'draw the line' when they're 15, let alone 35. You have all those years of habit and expectation to overturn... He will complain, you will feel guilty... But if you want a life, don't let that stop you. Draw your line, tell him X needs to change, tell him he needs to move out - whatever you need - it is your turn now!
Also, be very clear in your head and with him that you will no longer tolerate any aggression. Call the police on 999 if he is violent or aggressive. They will take you very seriously. reallytired is right that this is domestic abuse. Recognising that you don't want to live like this any more is the first step... Good luck.