Dealing with coworker

I am struggling with my officemate. We spend 8+ hours per day in the same 10x12 room. 5 days per week for the last 4 years. How can I stop being bothered by the fact that they constantly bring up politics in conversation? They also think they can micromanage everything I do despite being a colleague and not my supervisor. It’s made for a tough work environment but I don’t want to go to HR and make it a bigger thing. I’d rather just stop caring but it’s so hard.