I work in the food industry on a shift no one else wants to work, but I am scheduled along with another employee to work 8 hours a day, 5 days a week. I am this other employee's direct supervisor and lead on the shift. We are down a person (we should have 3, instead it's just us). The workload is heavy without the third person, but I have for years been overworking myself (ex: skipping all my breaks including an unpaid lunch at the worst of it, consistently getting OT, and helping my previous and current coworker/s with their production before finishing my own.) I feel like I'm overhelping to my detriment so I decided I needed to set my work and life boundaries for a better balance. I've stated I'm going to get all my breaks in regardless of if it puts me in OT, I'm going to get my work done first before helping anyone else with their workload(within reason, I will train and explain production and such), and last, but not least, if my coworker's list is manageable, as in I could get it done easily, then I will work on something else.

Lately, this coworker makes me feel as if they are taking advantage of me by asking for the bigger product and then going so slow on it that I have to swoop in and finish the task for them or help them with the brunt of it. This coworker has also told me things like that if they show up late they will purposely not clock in and act like they forgot then go back and fix their time on the time clock. They have also expressed to me that they will hide in the bathroom to take up extra time at work. My question is: Am I an AH for setting them up with a manageable production list and then finishing my larger workload and not helping them complete their task for the day? I feel like maybe I should have been better about vocalizing the last boundary I want to set? They seemed pretty mad at me, but I am feeling like I'm being taking advantage of constantly by this coworker. Any advice would also be great. Thank you for your time.