dear daughter,
i am worried that you may be worried your mother will kill herself ("there's a gun in the house"). i am worried that if she has a bad accident or one day does take her own life, that you will struggle with wondering if you did enough or said the things you needed to say.
everyone here will tell you that love does not make an addict well. the longer addiction progresses, there is a hard thick wall around the addict. the disease protects itself by building this wall so the concerns of others can't penetrate.
what concerns me is your mention of the gun. if you are worried your mother may use it to commit suicide, you can ask a family member to remove it from the house. guns should never be in the homes of active addicts or anyone with major depression.
and you can always send her a card, now and then, to ease your mind that you have stayed connected as best you can. it is important you protect your fragile heart while at the same time you try to do what is obviously very important to you: honoring your mother.
i am sorry she has hurt you and so many others. i am sorry you do not have a mother who is there for you. you sound like a lovely girl. you can still live a beautiful life.
take good care of yourself. going to some al-anon meetings or seeing a counselor can help. do the best you can.