HiCustomer Thank you for asking your question on JustAnswer. By the way, it would help us to know:
-How long have you been together?
-Why is it ending?
-Could you explain your situation a little more?Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
I would sit down and write him a letter after you have left telling him all of the reason you left the relationship and how what he did to you over the years has affected you, it's not only closure for the relationship it's part of your healing from the abuse and being able to find the courage to continue to move on with your life. Make sure this is goodbye and that you won't for whatever reason go back again because if you go back after this goodbye letter he may make it worse for you. You have finally realized that you deserve better than what he gave you all of these years and it's NEVER too late to find happiness no matter your age. Make the letter as long as you need it to be to get all of your frustration about the unhealthy relationship out in the open. Explain to him that you had to write this letter to final find closure so that he knows that you mean what you said and this time there will not be another time.
As far as the legal things you will have to talk to a legal expert to find the answers you need for the legal side of the relationship but I would not wait until you got legally divorce to leave that can come later it's important for you to go and go now so that you can be safe from the abuse you have endure for so many years and get a fresh start. I would worry about leaving and then give yourself about a week to relax and get settled in and have all of your things you are taking with you so that you don't have to go back once you are gone and then write the letter to him and suggest that he gets help and that is the only way he can find someone and truly be happy is if he gets the professional help that he really needs.
You're welcome and I hope you get the closure you need to move on and find someone that truly loves you cares for you and also treats you better than he did. You may be sad about the relationship ending but it's best for you to be healthier and happier. Saying goodbye is always sad no matter what the circumstance. Good Luck to you!