Do you have a substance abuse problem? If you even suspect that you might, the best bet is to seek a professional to get some advice on how to proceed. It is a difficult and painful process to admit you are powerless over anything let alone to be addicted to something you feel shameful about.
It does not make you any less of a person if you do determine that you do have a problem. There are so many great organizations and options to help get you through that first step of admission. If you have issues with heavy withdrawal symptoms, it is imperative to seek medical assistance. This could mean life or death.
Another important aspect is having a solid support system around you to help through your recovery and long-term sobriety. Many times a spouse or significant other may not be as supportive as you want them to be, but understand that even though you are the addict the whole family has been affected. There are programs such as Al-Anon and even programs for children to cope with the feelings that they have associated with the effects of the addiction on them.
It is critical to do some form of group therapy or finding a recovering addict to lean on. You need to have others that understand your struggles, temptations, and trying to lead a lifetime of recovery. Understand there may be set backs, known as relapses, but it is not the end of the world. One day at a time, and sometimes it is one second at a time. Always reach out for help.