AIO about my brother going on vacation instead of staying to help me with mom's surgery

My mom (57F) is having hernia surgery next week. I (24F) live with my mom while in grad school and working two jobs. My brother (26M) moved out right out of college and now lives about 2 hours away with his fiancee. Parents are divorced, mom is currently single, and I am have no contact with my dad.

The issue is that my brother is going on vacation with our dad the day after mom's surgery. I originally had asked him if he could take the weekend off work to help me with mom's recovery and he was very avoidant as he had not told me about the trip. Eventually my mom and I found out that he was going on vacation with our dad, which is upsetting but I am more so upset that he just ignored me instead of being upfront with me and telling me about the trip.

For context, it is hard for him to get off work and I felt bad asking him to come help that weekend, but I have a lot on my plate and could really use some extra support right after the operation. I personally feel like he should not go on this trip and come help us instead, especially since he already has the time off work. Since our parents got divorced in 2020, I have been home helping to take care of my mom while he runs around doing whatever he wants. We never ask him for anything and my mom does everything in her power to support him (calls every week, helped pay for his car/rent when he first moved out, etc.) and he does not really do anything for us- never calls my mom to check in, barely texts me.

I am obviously biased and can't tell if I am overly angry about this. I just don't really understand how he can go and enjoy his beach vacation while I am here taking care of our mom all alone. I would really appreciate some outside opinions on this!!! Thanks for all feedback