Please go back and re-read (many times) Marda's excellent advice.
J., all I can say is that I've been there, to some extent. I made choices which led to my own unhappiness because I didn't play by the rules. What on earth stopped you from saying, when you filled out the paperwork for the lease "Hey, sister needs her own form so they can do all the background/referrals work on her too"? Even for your own protection, so should she damage property or skip out, you would be covered?
So, chalk it up to live and learn. I think you have bigger problems on your plate, namely two things Marda pointed out:
1. "I find what you're doing abusive not only to your sister but also your son.Those women had a difficult life and continued to be unhappy because they didn't accept responsibility for their lives."
and
2. "Until you accept responsibility for your own life you will be unhappy your whole life. Maybe you like to be unhappy. You have the power to change your life and be happy. Wouldn't you like a happier life?"
Take the hard look in the mirror, J.. I used to do the same thing: blame everything on everyone else instead of accepting the reality that in most situations, *I* am solely responsible for most of the outcome.
Be responsible: you chose not to put her legally on the lease. You chose to treat her like a child. If you choose to infantilize your son in this way as he grows up, you are going to have a terrible relationship. You can't just nitpick other people for your supposed 'peace of mind'. It's really about being controlling and you don't seem to have the capacity to manage and control your own life right now. I'm not saying that to be mean, but because you *have* let a situation become utterly out of control because it wasn't convenient for you in some way to ensure she was legally on the lease.
I'm sort of wondering if she's had prior episodes which you felt would jeopardize your being accepted for the lease at all so that you might have left her off?
I really don't know what to tell you, other than start with yourself. Take the time and effort you might spend on taking your sister to court and get some help. Maybe consider contacting the university in Spokane and see if they have no-low cost counseling services. Until you get square with YOU, your situation will always be plagued with people who are upsetting you, disappointing you, etc. Admit to yourself that it is the series of decisions made by you that have landed you where you are and decide what you want to do so that you choose more wisely, make better decisions, and take responsibility for yourself. Believe me, I'm living proof-- if you truly want to turn things around, it WILL happen. It's a lot of work and hard work, but the payoff is monumental.