Mom really hurt my feelings

So my mom charged me to watch my son while I was in the hospital delivering my new son that came at 29 weeks. I didn't really have much money so I gave her 20 and she was really mad said it needed to be atleast 40, even though it was only 2 days. Idk I'm feeling really hurt, my so's family is so helpful and happy and it just feels like my parents could care less. Has anyone else ever experienced this? 
Thanks everyone, I also don't feel like my mom has to watch my kid it just hurt that she charged while I was in the hospital, she doesn't have a job and she lives with us and we pay her phone bill and also give her 75 a week so she has spending money. I didn't spring him on her he came to the hospital with me I had to be put to sleep so he couldn't be in the room or stay. No one was allowed to see baby not even me so they both went back to the house, when I got out of the hospital that's when she asked to be paid.