There’s a lot there and it’s difficult to formulate a response because your question isn’t completely framed. You asked "how can I explain that? There are many ways that it can be explained but you are the only one who can determine how YOU can answer. What you have written here shows no remorse because you pretty much say that you would continue if you thought that you could get away with it. That’s a really poor attitude and doesn’t reflect well on you as a person.
What I see when I read your post is that you don’t think that rules apply to you. That isn’t good for someone trying to keep their clearance.
You don’t say anything about what the current status of your clearance is. Do you have an SOR or LOI?
A few suggestions . . . Get your ass into counseling. You can do drug and alcohol or just straight up therapy. You say that you don’t have a problem with alcohol but you do and you need to learn that if you want to stay in this industry. Next, talk with a clearance lawyer. Even just a free consult for now. Third . . . I don’t know what your qualifications are but you need to explore employment outside of the cleared world.
I don’t say any of this to be a jerk or to hurt you. You need to get your head together if you want to keep your life together.