Never get to see my niece and nephew again?

Okay this is going to be all over the place because I am beyond upset. So I work from home, which allows me to watch my niece and my nephew for my sister while she and my brother in law get all their "finances straight". She pays me a very small amount to buy diapers For my niece and food for the week for both of them. Well I have been the only form of daycare for them for the past almost 7 years. I am ALWAYS there when they need me. Kids have a doctors appt? Sure I'll take them. You have to work late? Well sure they can stay the night with me. I guess it's my fault for creating her into this monster. I never say no to her and neither do our parents.

Well today, my brother in law (who very much dislikes me) got sent to the ER because his blood pressure is really high and they want to monitor him for the night. My sister said she doesn't want him to be alone so the kids "HAVE" to stay somewhere else. Didn't ask if someone would keep them, just said we had to figure it out on where the kids will be staying. My mother is in "open enrollment" for her work so she is working major overtime, and my brother in laws parents are out of town. So when it got put onto me my husband quickly reminded me that we have a company dinner for his work at 7:30. So I had to be the one to tell my sister that sadly nobody will be able to keep the kids for her and he will just have to stay at the hospital by himself, I mean he is in no immediate danger and he is a grown man. Well this is the first time she has <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> gotten a complete no across the board.

I'm the one that got screamed at that I'm not there enough and there's no reason for me go to the company dinner. Basically trying to tell me I have no choice but to keep the kids. I proceeded to tell her no and she pretty much told me that I'm good for nothing, I just watch the kids for money, and she'll be coming to get the kids and I won't be see them anymore. She then decided to dig into me a little deeper by saying "once you actually have your OWN kids you'll understand", knowing full well we have suffered four miscarriages in the past two years and have been trying for 4 years. As much as I like to think she's just being over dramatic, she has NEVER been so mean and hurtful to me.

I don't understand how being told NO for once in her life turned into such a war. I love those kids more than ANYTHING. I know they aren't mine but I love them as if they were my own. Honestly I'm at a point where I don't want to help them out anymore because daycare is going to be about 1300 a month at the place they were looking at a few weeks ago and I'm only making them pay me 100 a week. If they want to treat me like garbage then they can go somewhere else. But on the other hand I will be so lost if I don't get to see my niece and nephew everyday. They're my best friends. 😔

I just need an unbiased opinion of the situation. It's such a stupid argument.

I'm keeping this anon because I don't want this on my profile. But if I want to reply to someone I'll post it here.