She's not now suddenly convinced that life IN FACT is awful, if she's now a little depressed it's because she's super heartbroken that her child has serious mental health issues that they aren't willing to address.

Depression, over the long term isn't something that most people can beat on their own. Start the conversation with your mom. Say "sorry, today was hard, I appreciate how hard you're trying to help me. I'm ready to get help." Things only get better from there.