it's made me a worse person

Not really, you're just a person and its understandable that you might feel this way when faced with the situation we find ourselves in. Beating yourself up is unlikely to help.

I'm kind of in the same boat as you are but I have found that taking smaller, less daunting, immediately actionable steps renders a lot more progress than larger leaps. You're the best person to decide what those small steps are but they can be things like attending a low intensity protest (recurring ones can be a safe bet, even if you have to travel a little way to get there), volunteering with local orgs (leftist or otherwise, food panties feed people, regardless of who runs them), or attending leftist educational sessions (some local socialist groups do teach-ins, not sure how common these are elsewhere).

Some may disagree with this, but being especially kind to the people around you is an anticapitalist action. Under capitalism we are in an alienated, adversarial, and competitive relationship with everyone around us. Stuff like stopping to help a stranger who's car broke down, engaging with a service worker as a fellow human being or handing out cash to homeless people are all small actions that make a difference and would be commonplace in a more cooperative society. This kind of practice makes it easier to break the social norm of "minding your own business" which keeps a lot of people from taking action at all.

You're never really going to remove fear, its more about getting used to it and doing things anyways. Activism is supposed to be something you do your whole life. While there aught to be some urgency to get out there and do your part you don't need to become an antifa supersoldier by this time tomorrow.

Good luck! you can do this!

Edit: you'll never participate in organizing "alone" you will find yourself with likeminded people. If being among strangers is intimidating then its not unreasonable to bring a friend or an acquaintance.