hon, he was homeless when you met. for all YOUR heroic efforts to SAVE him, to CHANGE his life, he returns to his normal. who he was before you met.
i'm not sure how a homeless, unemployed, abusive addict rates as a FIANCEE. someone you would want to marry and tie yourself to legally and all that.
when people show us who the are, BELEIVE them. if I recall, this isn't your first rodeo with this type of individual.
maybe the change that needs to happen is with YOU?