has happened to me but as a person who (i think) got through it, here's some advice:
1 - This sounds like bullshit but do your best. Like f**king just don't say stuff unnecessarily. Even if you need to act, pretend. Eventually this pretending will lead you to actually think it's true, making you better.
2 - This helped me a lot: help people. I'm doing my best to help friends and family with stuff, even if it's small stuff like chores. If you help others you're helping yourself
3 - In short: Do your best.