I’m not the best at advice, but for me, the first step is internal validation. When we suppress our feelings, it can become easy to resent them, which is understandable. However, sometimes this turns into self-loathing or irritation toward having those emotions.
Your frustrations are valid, and it’s also important for you not to beat yourself up over your feelings or what your mom said to you. You’re not your sister. It’s not fair for your mother to make comparisons like that as a means of criticism. It’s okay to say no and assert personal boundaries. Your frustration and fatigue are understandable. Unfortunately, some family members respond poorly to boundaries that they feel inhibit themselves and others, and it can be tempting just to not set them up to avoid drama and conflict, but being persistent can work. Some family members are more stubborn than others, but it can work with consistency.
Another thing is coping mechanisms, which is hard to determine because these are vastly different for everyone. Me, I write, watch movies and YouTube videos, and play games. Sometimes, I take a walk. I saw you love writing, so maybe that can help.
Hoping for the best. <3