Girlfriend goes on trip with some friends

I stay home

We keep texting

One day I decide not to text her first

I get no texts all day from her but I do keep in touch with my other friends who are on the trip (men and women). I even get pictures from what they're doing. I think nothing of it. I was not checking up on her. I was just randomly chatting with everyone there.

Next day I talk to girlfriend. I ask her why she was off the grid for a whole day (she's usually a complete texting addict).

She lies to me! A lot. I don't understand why.

"I was sleeping until noon"... "No you weren't. I know you all went shopping in the morning"

"Oh yeah that was after I just crawled into bed because I was sick." ... "You're lying. You played boardgames with the others afterwards"

"WHY ARE YOU SPYING ON ME? I was just feeling tired and sick!"... "Why the fuck are you lying this is a picture of you laughing and partying on that day"

"YOU ASSHOLE! WHY ARE YOU BEING SO HORRIBLE? WHAT KIND OF MAN SPIES ON HIS GIRLFRIEND" bla bla bla

Every step of the way she lied to me and I knew they were lies. She lied about the most mundane shit imaginable and when she couldn't lie anymore she exploded.

What the fuck? There was no reason to lie. This makes no sense.

I want to break up with her because of this but everyone is telling me I am exaggerating. Why would she lie?