i’m desperate for advice PLEASE help 😔

i have a 3 month old son and I’m a stay at home mom. for extra spending money, i’ve decided to watch my niece monday-friday for $100/week. her parents took her out of her home daycare and the day she left, the owner of the daycare said that if it doesn’t work out, to let her know and she can try to make something happen.

it feels like this is not working out. my niece is an only child, very spoiled and she’s also used to having all her friends during the day. the only friend of mine that’s available during the day with children, lives an hour and a half away.

my niece has already started lying to me. she’s been acting out much more frequently (telling me no, deliberately not doing what I ask and lying about everything she can)

also, my niece also FREAKS OUT when my son cries/needs me. she’ll be playing with her toys and the second my son cries and I pick him up to fix what’s wrong, she stops what she’s doing and tells me she needs me to put him down so i can give her attention. ever since i’ve been watching her, i’ve had a very hard time giving my son any attention. I play with her extra hard when my son naps, but she still wants all the attention when he’s awake. I try to get her to play with her toys by herself, but after 5-10 minutes she wants me again and cries because she clearly misses having other toddlers to play with. she keeps telling me “it’s not fun here” and that she wants to go home. i play with her, she has a million toys over here, we do arts and crafts and go out of the house, but she still refuses for my son to get any attention. it’s causing me to be extremely depressed because the whole point of me staying home is to raise my son, but at night i cry because he didn’t get near enough of the attention he needs/deserves. it hasn’t been long since she’s started staying with me during the day, should I just tell her mom that she can’t handle this environment and needs other children to play with and try to go back to her daycare? i’m so lost and sad over this.. my son doesn’t deserve this and she deserves to be where she’s happy. the reason i’m leaning more towards her going back rather than waiting it out to see if she’ll get used to it, is because i’m worried if time goes on and it stays the same, the daycare will be full and she won’t be able to go back at all. but I need people with a clear head to tell me what they think. i feel I may be too deep in my emotions to think rationally