I'll try to keep this brief. We've known each other since Feb '19, she was a former client of mine and we worked very closely, and ended up becoming very good friends, before anything sexual happened.

I'm 24, she's 20, I've got a much higher SMV than her for sure and she pushed for commitment very hard. I did give in a little too early I feel, but I felt optimistic about things based on what I knew about her.

Flashback to last week, she tells me that she texted an ex-fling (he was very high SMV, gave no committment, and alpha-widowed her), congratulating him on a very big achievement. I was taken aback by it, but didn't want to make a big deal of it at the time, especially because she told me upfront. The rest of week I still had a gut feeling that something off, she was being A LOT less needy over texts, and they were liking each others pics on Instagram now.

We spent Friday, Saturday and Sunday all day together, things were great, lots of sex etc. I also looked through her phone and saw the string of texts with him, about 10 texts back and forth but it was all congratulatory. She was the last one to send a text to him.

Then today and tomorrow, that gut feeling returned. So I messaged her today telling her that her initiating contact with someone she used to sleep with is not ok and that it's best if we end things. She then tries to justfiy why what she did was innocent, and that she was willing to not do anything that would make me uncomfortable, and the conversation was actually going somewhere until she slipped by saying

"It was one text. I did not continue a conversation. I would have sent it to you if I still had it but I delete my phone messages once a week because my phone storage is full. Why do you not trust me?"

I clarified by asking "so you sent him a congrats text, he replied, and there was no further communication after that?"

She responded with "Yes, I've said that.", to which I replied by telling her she just lied to me and never to contact me again. Then I blocked her off everything.

I'm not too sure why she lied about only sending one text, given that the rest of the texts were innocent but it's still a boundary that she crossed and then LIED about. I can no longer trust that she is not communicating with him and I'd rather be single than to worry about that.

Did I handle this right? Also, for future reference, what is the best way to establish boundaries without mateguarding?