Context: My two sisters 23F and 28F both made babies 2023 and 2022 respectively. The babies are now 11 months and 15 months. And I am 20F.

My long distance boyfriend came to visit me on the 24th and he stayed until the 1st. When he left yesterday we were both so heart broken and we both still are. Both of our lives are filled with so much disappointment and it was a hard kick in the face to go back to our lives. I spent the whole of yesterday sobbing and i felt so tired today that I slept for the majority of the day. I only just woke up a few minutes ago because i realized that my phone had died( I was on a call with my boyfriend). When I woke up my sister 23F is telling me if I am ready to watch BOTH the babies tomorrow. I was incredibly confused so I asked her why? And she was like she starts work tmr, so does my sister, mom and dad.

I have babysat the 15 month old for about 10 months of her life all alone. And that period in time was so stressful and depressing for me. The 11 month old only just came to visit us in november because she is not from where I am from. And my family loves asking for favours from me 24/7 so you could imagine all what ive had to do. They take advantage of the fact that i love my nieces and that my love language is acts of service. They literally abuse that. So I told her no and she proceeds to ask me if im going anywhere tmr. I found it incredibly inconsiderate because i just went through something that literally feels like the worst pain. Am I the asshole for not wanting to babysit them? Feel free to ask for more context