Feeling used and upset.?

It is completely justified to feel used in this situation. Your friend didn't ask, and that is in no way right. But if you do not feel comfortable watching her kids when she asked (well didn't ask) in that way then you need to confront her ( I know this will be hard i have a lot of trouble confronting or telling people no too) I would say this. "Hey (enter friends name) I am going to have some problems watching (enter kids names here) because we are really trying to save money for college. Is there anyway you could send them with extra food or snacks for after wards? And maybe some school supplies? I really hate to ask this but there are a couple of problems. And i don't really think i would be able to watch them every day. Is there any way we could work out a schedule?" Ok the more i read that the worse it sounds but you have to confront her with something like that. You can't let her think that you can just be used like that.