Want a divorce.

My husband has mistreated me for years. By mistreat I mean emotional abuse and many transgressions against me regarding fidelity. We have 3 kids and after 10 years I can’t take it anymore. I want to divorce him. Idk how to go about this. I have wanted it and decided this before but each time didn’t. Now it’s genuine and idk how to tell him because I know he will think it’s just another one of those times where I’ll end up backing out. I know serving him with papers would be evident enough but he won’t take me seriously if I tell him before which I need to do. Any advice