I want a divorce, but i'm afraid to tell him. how do i go about it without him convincing me to stay again?

Psychotherapy: In therapy, you could discuss e situation so to clarify how realistic are your expectations ( in each of the alternatives), and what you really want, among other topics. Find a good therapist in your area. Good luck.

I would: Consider getting counselling. You may just have to leave for your own mental health. If there is violence involved, you need a plan. Good luck.

Get 2nd opinion: Seriously! get a 2nd opinion: talk to your friends, family, religious leader, counselor, physician etc. Once you're convinced, pull a katie holmes & find a divorce attorney to get proceedings going. S/he can take it from there. Of course, you know him better than anyone else. Is he going to fly off the handle? Make sure you have a place to live + money to live off before you tell him.

Counseling.: There are several possible approaches. One can seek the advice of a divorce attorney, a therapist or even ones physician if there is an established patient/physician relationship.

Boundaries: I would seek out a Psychologist and present your issue and concerns about being convinced to remain in a marriage that you don't want to remain in. Boundaries are key here and being strong enough, having the proper supports, and a means to remain firm are often difficult to assess and develop strategies for.

Do your homework: To build your confidence consult first with a divorce attorney. Get as much information as possible re finances, child custody, etc before you confront your husband. Your backing down may reflect your own insecurities which will be less if you know more about what to expect, worse case scenario. Get as much support as possible from a therapist, family and a close friend or two.