Lots of people dont get over depression and end up dead. Robin William's, for one. Many others. One does not just get over depression. It requires treatment. Some people are able to do treatment on their own using different tactics. Some require professional help. Myself and many others on here can tell you about times when we could not care for ourselves due to depression. Depression does not care how much money you have. And seeking help is very difficult for exactly the attitude you have about it. The stigma that we should just get over it prevents many from seeking help.

But you're absolutely right. It's not your responsibility to help her get treatment. So let her be depressed and deal with her son. Just keep saying no and holding to your boundaries. It was nice if you to give her some resources, but now it's on her to seek help.