Ask them, "Hey guys, heard you were having a sleepover...why just you three?" Boom
So tonight my 3 best friends had a sleepover, and didn't invite me..We always have sleepovers together, I cried for hours, I feel so left out and I don't think I did anything wrong to them. What should i do?
I'm sorry that you feel left out, however, your friends have the right to have a sleepover or go to a movie or etc. Without you. Getting upset about it doesn't help.
There are going to be times where you feel things aren't fair. That's just how it is. If this happens consistently, you might want to ask about it. However, if this is the first time that you've been excluded, it could have happened on the spur of the moment. Crying for hours about this seems a little over the top.
It's not as if they've decided not to be friends with you any longer. It just means that they had a sleepover without you.
This is going to happen throughout your life. You need to decide if the circumstances warrant you losing it each and every time you are left out of something. In my opinion, it would sting if this were to happen to me, but it's not life-altering. It wouldn't affect my relationship with the three unless I felt like I needed to hold a grudge over something this minor.