What active steps would you take when your addiction made you hurt someone so deeply that they will never speak to you ever again or forgive you... The amount of guilt is overbearing. For those who have had this experience and are many months or years sober - would love to hear from you! 
Iβve hurt many people very deeply. Itβs always the ones closest to us that we hurt. Prayer and living amends are the only thing that can be done when others chose not to forgive. Living amends can be very strong. Prayers are as well 

The 12 steps of AA address these types of things. If you are unfamiliar with them, try to find meetings to go to. There are people there with sober time that will be willing to sponsor you and help you work the steps. The steps help us to deal with the past, make amends, and fix our character defects, all while helping us to stay sober.
The 12 steps are in the order they are in for good reason. Work the steps. Lee and Shawn are correct in regards to amends. Lots of work to do before you start mailing those letters though.