I can really hear your desire to get better. That is wonderful.

The next step is to build a plan. Its very hard to build a plan on your own. I would advice you to look for a counsellor or a support group who will support you in building a plan, help you to implement it and give you tools, encouragement and insight.

They will also help you identify barriers to change and think of ways to tackle them. Such as - your mother in law (who sounds very unhealthy to me. she does everything she can to enable dependency and keep people where she wants them. she control everything. including you. she treats you like a child. you are not a child. she encourages your drink and wants you to serve as a drinking buddy. the truth is that she is using you.)
Also - your lack of self esteem and lack of confidence as well as your thought process.

I know you want to change. I know you want to take the steps necessary - please seek help. If you dont - you will end up deeply depressed and unhappy, drunk and child-like all your life. You deserve a better future!