Friends leaving me out?

[Paperplanes]

Ok basically a group of like six of us go out every Friday night after school then this week they literally made plans in front of me without inviting me - later I heard they thought I was babysitting so whatever and we have the friendship where I would usually just invited my self but it felt weird this was Thursday then last night we were all planning on going out and why I asked my frond that day she was just like oh sorry I can't come I don't think she lied but still it's rude not to say till last minute and then tonight I wasn't invited out at all but saw a photo on Instagram of all of them going out