So I am in a conundrum

2 Year LTR lied to me. It was a fairly basic and inconsequential lie but I am a bit confused about how to deal. I'll explain in detail.

So both of us were in our college town, and meeting friends. She had to meet a girlfriend of her's who lives with her boyfriend. My LTR has previously had a thing with the boyfriend 3 years ago during college. Now she tells me that she is going to meet her friend at her house to which I immediately react saying maybe you should invite me and we will have a threesome. I leave her then and give her silence over text. 30 minutes later I get a text from her saying "meeting her outside, but there is no need to be so sarcastic and a jerk about it, make your objection known in a more polite way". I reply okay to this and give her more silence. Later that night I had to leave for my hometown and couldn't get tickets cuz of some family drama. She helped me through it and got really expensive tickets for me and we stayed together during the night at her place.

Fast forward to two days later, where everything is fine and I am showing her a new gadget I got. It slips out of her mouth that she has already seen it at that friend's place. I immediately confront her, telling her that this isn't okay and she can get out. Drama ensues and then I ask her to show me the text where she asked the friend to meet outside. She refuses saying there is no point cuz it's fucked now anyway. I think I got gaslit here cuz she spewed some shit about trust and I relaxed my stand to hey just tell me about what happened that day and I will be fine. She gave me a detailed account of how there were two more girls and her boyfriend wasn't there and they went to a local dunkin donuts. I believed her but there were bells ringing in my mind because dunkin had closed most of the outlets in my country. I checked online and fair enough there is a dunkin operating in the area where she said she went to.

But I still had to verify. Now I went through her texts two days later, i.e. today and found out that the friend asked her to come home because she was too broke to go outside. My LTR NEVER ASKED HER TO MEET OUTSIDE. To be fair to her there is talk right after that about how nice it was to meet the other girls as well.

But I am still enraged and feel disrespected. She is sleeping rn and I am thinking about what to do. I have the following options:-

  1. Let this one slide but be extra careful in the future. If I detect a lie ever, I'll dump her.
  2. Immediately confront her in the morning and whatever happens, happens.
  3. Let it slide for now but start meeting other previous hookups who she is insecure about and lie about it. Make sure she detects the lies and when she confronts I'll tell her this is how it feels and then whatever happens happens.

Right now I am leaning towards 3rd but I also feel guilt because I have lied about such inconsequential shit to her as well and a fuss has never been made.

I have abundance so I can go single anytime but I do really like her and want this to work. However, I think my feelings might cloud my judgement which is why I am asking you guys.

Before anyone asks, I regularly verify whatever she says and never have I had an ounce of doubt or anything so there is no history. I just feel disrespected.

Or maybe I should sleep on it and make up my mind in a while?