I resent my coworker and badmouth him to our boss when I get the chance.
What did your coworker do that pissed you off?
I'm working in the same job with him for years and I feel like he's taking my reputation because he got promoted before me. Its just not fair.
You shouldn't badmouth coworkers because most of the time people will find you to be unrelatable and devious. Plus it comes off as a bit unprofessional. Therefore, it might even make it harder for you to get that promotion because people including your manager will just feel you are a person with too much negativity.
F***k this. I should just sabotage his work.
I can understand your frustration, but it is unprofessional of you to talk badly about your coworkers with their boss. That will not look good when it is your time for a promotion. He could have deserved it, but that would be something you talk to your boss about.