You've made the decision, you talked it through with your support group, you know deep inside you that this is the right thing to do and you're ready to break free.
Congratulations! You've already taken the first - and potentially most difficult - step to break up with an abuser.
You've had break ups before, but trust me, this one will be different. You won't just leave and figure out things amicably; abusers want things done their way. They haven't allowed you to get the love, the safety and the joy you deserve. Now they will try to make moving away from them as difficult as they can.
The second step to breaking up is to think of all the things that tie you together, and cut all the bonds. This may seem like an exaggeration but here is an example of how this may turn out:
You live together and you move out without taking all your possessions
Initially, they say it's fine, take your time. Next thing, they send you long emotional messages about how they can't handle looking at your things and it's so selfish of you to not properly move out. You panic and say ok I'll arrange to pick them up. Next day, they say it's fine you don't need to pick them up, it actually doesn't bother them at all.
If you send your friends to pick up your stuff they will make it as difficult as possible - because they want YOU to go over so they can emotionally manipulate you again (or worse).
They may destroy your possessions.
They made hide some of your possessions so that you will have to go back.
Abusers, especially if they have some personality disorder, will find any reason to contact you. They will find minor details to obsess over that you can't even imagine. I gave my engagement ring back to my ex and told him that I don't want anything to do with it including any money from the sale. His way of dealing with it was obsessing over the ring designer and stalking their social media. He found a tweet from months ago which filled him with anger. He kept sharing all this with me despite me saying that I don't want to be involved. Then, he kept updating me about his research to sell it and the money he made. According to him, selling the ring was really important because it could be like a plaster to heal us from this break up (seriously WTF).
Do you need any of this drama? No. So you have to cut all ties.
Do you live together? Plan moving out ASAP (and I mean ASAP). Do you have common accounts? Separate them. Do you co-own furniture? Split it or give it away, no furniture is worth your mental health. In fact, it is quite possible that if they owe you money they will never pay you back. Again, your mental health and happiness is worth it.
Of course, if you have children together things will get more difficult. If you can take the children with you to a safe place, do so, and ideally get some legal advice (please find some free UK numbers for help at the bottom of this post).
Important note: There are circumstances that do not allow this to happen. When things have gotten really bad you need to urgently get out of there for your health and safety. In this case, please do what you feel is the safest immediately rather than waiting.