Oh man, I feel you.

Given your situation, I can see only one way to do this: go full-ninja and disappear.

Stealthily find a job somewhere - away from where they expect you to be. If you have a cellphone, change phone numbers (and providers if you can). Find another apartment without them knowing. If you need to, make yourself a new email and Facebook account (I recommend against the Facebook though because they could find you too easily) And don't contact them again until you have your life sorted out.

Yes, it's going to be hard. Yes, you will miss out on live some more. But after that, your life will be yours - you will have the money, resources and will to say no to them and to work around the shifty business they will do to continue their behavior behind your back.

So unless you can reason with that narcissist mother, and somehow make her accept that you're an adult now and need to live for your own, it's easier to fly under the radar. And who knows - maybe the worry of a few months, if not a few years, without her son/daughter will make her see how toxic she was.

At any rate - best of luck with your situation, and I hope for a decent resolution, sibling-in-arms. You've done me good, in the past - I, too, am there if you want to talk.