My husband of 13 years is an addict I want to file for divorce how can I make sure I get full custody of my two young daughters?

No competent lawyer would ever give a "for sure" response to an email inquiry with this few of facts.  For an explanation of the relevant legal tests, procedures, and links to the statutes, etc., see the information posted here.  Beyond that, you should schedule a full consultation with a family law speialist and go over your entire case, top to bottom. so you understand every issue, possibility, risk, cost and benefit.