In my personal experience, a sociopath is USUALLY violent, but can also be controlling and domineering without violence.
Your experience with leaving him will be very similar to going through the stages of grief. You will feel guilty, you will be angry, you will go through a phase of self directed anger, where you wonder why you wasted so much time on him, eventually, you will find relief. Then you can move towards peace.
The best advice I can give you, though, is that you need to take the time to make sure that you are emotionally healthy and strong again before you start another relationship, especially after 15 years of catering to a narcissist.