Friended someone of facebook by accident?

[Jack]

Ok so I was on my friends wall looking at his old pictures and crap and I noticed one with a bunch of comments this was like in march the pic was posted so anyways Im on my phone and I click on one of people who were in the argument and it was my friends cousin's girlfriend. I guess I might've added her by accident since it was on my phone and my thumb might've pressed it. So about a few hours later my friends cousin messages saying "don't friend my girlfriend you little shit". I was really confused and worried and went to her page and it turns out I did, I canceled it right away and told his cousin it was a accident. I'm really worried right now because I don't know if my friend knows I was actually going to see him tomorrow since he moved and is visiting his family. My friend hasn't texted me yet but I'm sure he will soon. My question is help me! What should I say when his cousin responds to me because I'm actually nervous. I don't want my friend finding out because I haven't seen him since August. I actually been to his cousin's house before he's pretty cool but he over reacted in this...
Also I guess his girlfriend might've told him
Wow he didn't even respond back I've been waiting 3 hours I don't know why he would send me it then....

[Katlady]

Um, the girlfriend is a baby if she can't make decisions for herself. I wouldn't worry about it, sounds really childish.

[Ethan Cha]

You could just tell him the truth. I mean what did you do wrong. It's the same thing with like butt dialing 911. It was an accident, what could you do?