Am I Obligated to Help?

My mom has temporary guardianship of my nephew and sometimes I watch him for her. I also have a 1 year old and a 6 year old of my own. It is very hard to watch him because he screams the entire time I have him which in turn causes my 1 year old to scream the entire time and my 6 year old acts up.

I also have a dog and a new puppy. My dad called me at 5:45 this morning and woke me up but I didn’t answer. Then at 8am my mom called me because she is sick and apparently my dad told her that I was going to watch my nephew for her today. I told her I never even spoke to him and that there’s no way I could handle watching him today with everyone else.

She said she understands but my dad will be mad that I said no so she’s going to lie to him and tell him my 1 year old is sick too. I feel guilty for telling my mom no but I know for a fact that I couldn’t handle him on top of the new puppy. It makes me mad that she has to tell my dad a lie so he won’t call me and yell at me. Every time I won’t watch him my dad talks crap about me and calls me selfish and a bitch.

The thing is my dad has absolutely nothing else to do but he refuses to watch the baby at all. The last 2 times I’ve been sick and I asked my mom and dad for help with my 1 year old they told me no because they can’t watch 2 kids. But for some reason I’m expected to watch 3 kids and a puppy that is still going outside every 30 minutes and chewing on everything and everyone.

I feel bad for saying no but I’m really upset that I’m going to be called names by my family because of it. Should I have said yes anyways? Am I obligated to help?