Don't want to be backup child care

Ok my friend calls me when her and her husband forgot about a meeting and needed to drop off 2-3 kids at 6am for me to get them on the bus to school. I have two of my own. I told her I would do it this once but she needs backup care for when her daycare won't work out. I can tell this pissed her off but this isn't the first time she's asked me for this stuff. I sub in the lunchroom at school but other than that I'm a sahm and I feel like she thinks I'm always there for backup. Honestly Imdont like babysitting other ppl kids especially more than 1. I really don't want to ruin our relationship, and my kids love her kids but I'm tired of having to run here and there and watch this one or that every time she has a headache or forgot a meeting or whatever. And 4-5 kids by myself is exhausting. Am I a total jerk? via /r/Parenting http://ift.tt/2nSzwAt