Getting your statements to come via email is a great start. You are on the right track. And it should involve little pain. Sooner or later, you are going to have to deal with your mother going wild again. There is no totally avoiding it. So long as you are living under the same roof, it makes sense to minimize tensions, so long as you are not giving up something you really want . . . like being able to date. On the other hand, your mom is not supporting you, from what I understand, so it's not like she has the right to set rules for you.

Eventually, you will get something in the mail. The next time she opens a piece of your mail, sit her down and have a talk. Tell her that she must not do that anymore. You know, this mail thing is a real red flag. In families where there is an unhealthy relationship between parent and adult child, that seems to be one of the main things that gets disrespected. I know of other situations where that happens. Even spouses living together should not touch each other's mail. That actually is the law of the land. Plus, it is healthy. Your mother is actually breaking the law when she opens your mail.

When you set a boundary with her, it's going to be a lot like you're the parent and she is the child . . . the spoiled child. Similar to dealing with children, don't put to much effort into reasoning her into what you want her to stop doing. Somethings should not be negotiable or debatable. "Because I said so." is a perfectly good reason when dealing with a child, or a childish adult. She will then proceed to test the boundary. You have to meet each test with consistent sticking to the new boundary.

Despite your mom's having tried to brainwash you all your life into thinking that you have no right to privacy, you seem to have very sensible and intelligent understanding of what should be the normal boundaries to have. So you are part of the way to your goal. You know when she is being unreasonable. You just need to follow through on what you, yourself, know makes sense.

Also, you have a little leverage, in that she wants to have you around. So, if she gets wild and extremely unpleasant, leave the house. Sleep in the car, or get a cheap motel room for a night. Then tell her that you'll come home when she calms down and acts reasonably. That might give you a bit of control. There's going to be fireworks, sooner or later, no matter what you do. You just have to tough that out. And I believe you can because you know your cause is just.