Hey askTRP, I'm looking for some advice on the state of my LTR and what I should do.

So, over this past Christmas holiday, my LTR (21/f) of 2 years flew back home to visit family while I (26/m) stayed behind in the city (California), so I decided to have a few friends over for Christmas.

I had my guy friend and two women I went to college with (my relationship with these girls is strictly platonic) over my place. I met up with my guy friend earlier in the day at his place, then we went to my place where I told my women friends to meet up with us.

We played board games, drank a little bit, played music, and had an overall good time, and during the night, my guy friend recorded a story to his Instagram profile in which me and him were having fun (relevant for later).

Anyhow, this weekend, my LTR called me to ask what I did for Christmas. Here's how the conversation went:

Her: "What'd you do for Christmas?"

Me: "Hung out with [guy friend]."

Her: "Oh... Did you see anyone else in the time I've been gone?"

At this point in the convo, something seemed weird, but I chose to stick with what I said.

Me: "I only hang out with [guy friend] on a consistent basis."

Her: "Ok... So you hung out with [guy friend]?"

Me: "Yes."

Her: "Did you hang out at your place or his place?"

Me: "His."

Her: "... Are you sure?"

Me: "Yes."

At this point, she starts getting very naggy, asking me the same "am I sure?" repeatedly. I tell her I'm tired and I'm going to sleep. I knew she knew what I did over Christmas, but I didn't like that she was testing me, so I decided to keep the full night of events to myself.

That next morning, I wake up to pages of texts from LTR saying how I don't care when she's upset and I don't put in effort in the relationship and how she knows I'm lying about what I told her I did on Christmas.

I ignore the texts and called her tonight. She tells me that her friends that she was hanging out with on Christmas were checking on their boyfriends and wanted to "see what they were doing" and they know that I never post to Instagram, so they searched for and found my guy friend's instagram profile, saw his story of us hanging out, and heard a woman's voice in the background. LTR then went to my guy friend's profile and saw/heard the same (they don't follow each other and have never even met, btw).

So, the current scenario is that LTR says that I lied to her (I didn't lie to her, but I did withhold information. She still chooses to see it as lying, however) and that her trust for me is fucked up and she wants me to apologize and give her my word that I won't do it again. I told her that I honestly don't care to prove myself to her after 2 years of being together and I won't apologize because I did what I did and I'm not sorry, and that I purposely withheld information because she felt the need to test me (In which she responded that she was "giving me an opportunity to tell the truth").

I told her that she could've just been forthcoming in telling me what she saw and ask me about it, instead of feeling the need to "test me" and ask me what I did, but is this too much for me to expect from a woman I've been in an LTR with for 2 years? My integrity has never been in question before in our LTR, so this is not a recurring thing.

A strong part of me says that this is unacceptable behavior and to leave the LTR, but I also wonder if I fucked up in not just telling her everything I did. Obviously I can't ask my real life blue pilled friends for advice, so I decided to come here.

Thoughts/Advice?