Good luck on your job interview.
If you aren't a good lier then what you tell them needs to be something you believe. Maybe you "Had the opportunity to take some time off to do some personal growth" writing, research (they don't need to know on what but they may ask), doing things you had always wanted to do but didn't have time to. You learned alot about yourself. You didn't plan on being out so long but before you knew it a year and a half had gone by and you thought it was time to get back to work.
If you did help your hubby with his business then I would really play that one up because you could have alot of for instances if asked. It was important to you that your husbands company get off to a good start and it is hard to afford good help when you just start out, so you jumped in where ever needed (since you were a manager), it was a labour of love. You feel it is at a point now and running smooth enough that you can persue your own interests again.
I would stay away from telling them about the addiction in any way. It is in your past and that is where it should stay if it has nothing to do with your job performance now.
Were you fired from the year and half ago job? Would they have a reason to give you a bad reference? I think you will do okay, you got the job you are in now.
Just believe what you tell them and they will too.