AITA - Group holiday issues

EDIT: I woke up to her going through my phone. I have nothing to hide so she found nothing, but I feel like this breaks the trust between us which is leads into an insecure issue we have been dealing with already.

Myself (M23) and my girlfriend (F21) have a holiday booked to Ibiza this upcoming June. There are 11 of us in total who have booked and it seems to be growing in numbers every few days or so.

We travel a lot, often in a group of 4 (also M23, M23 <both single>).

This morning, a 12th person (F20) was added to the group chat who my girlfriend dislikes. This person then books the holiday as she was given the booking information through direct messages by M23 without myself or my girlfriend knowing.

My girlfriend kicks off and leaves the group chat, asking me to remove her from the booking. She is fuming and starts ranting about the situation to me and others over messages who are aware of her lack of fondness towards F20.

She has now gone to bed whilst I'm being made to sleep on the sofa, shouting that I don't ever defend her and always stick up for other people instead, especially my friends.

Before this outburst, I had already asked my friend privately, why he would add her to the group chat and give her the booking details if he knew it would cause unwanted drama.

AITA? I never disagree with her in public but I will stand my ground in private when I believe she is being out of order or being dramatic over minor things. With 12 of us booked to go, probably around 20 people by the time June comes round, surely she would barely see F20 on the trip anyways?