But lately I've been in a rough state mentally (I say lately but it's always been with me) and having GPT guide me and being able to just dictate what I think helps me a lot on various levels, for various reasons.

You should consider journaling and/or a support group and/or professional help. You say it's always been with you, and relying on an LLM to help you parse your thoughts is only going to lead to bad places. It does not have the knowledge or skill of a psychologist, even with its vast database. It doesn't "know" the correct way to apply psychological concepts or know when you're engaging in destructive behavior, and it could even reinforce those same behaviors. AI can feel like a friend to talk to, but it's an illusion.

But at this point, using ChatGPT with a mic, isn't this basically cancelling every effort I've made? (using it in the first place anyway)

If you're telling it your deepest secrets and current problems, yes. You're putting your personal information out there for a profit-driven company to use at their discretion. Several people have suggested self-hosting, and I would agree, but ultimately I think you need to seek human help for the root cause of why you're leaning so heavily upon AI.