My (27M) GF (29F) has profound trust issues with me and I don’t know what else I can do

I’ve been seeing my GF for about a year and a half.

It all started when we did MDMA together with two of her friends who I hadn’t met before. That night, one friend was having a meltdown about something so my GF was with them in another room.

I was left with the other friend (let’s call her M) and had a lot of misplaced energy that needed to go somewhere. We had a good conversation and among other topics, she asked me about how my gf and I had met and I asked about her dating life. The next day I ask my GF what kind of guys M might be into.

I didn’t know at the time but she had heard our convo and assumed that I was flirting with M, and then me asking what kind of guys she’d like clinched it - my GF was convinced I wanted to cheat.

I hadn’t seen or talked to M since (and this was over 6 months ago) and it was only recently revealed to me by my GF about how she lost trust in me after that night.

A few examples of how that’s shown:

• I had to go to the dentist and she thought I was lying about it. Had to show her a text from the clinic to placate her
• Said I was talking about other women a lot lately because I A) mentioning having a nice chat with political candidate who was canvassing door to door. Mind you this is a woman in her 50’s B) mentioned a mentor of mine at work leaving the company who happens to be a women
• Is scared to let me go to a friends birthday weekend at a cabin they’ve booked with 30 people because she thinks I’ll cheat

I’ve tried being very delicate about it all, saying her feelings are valid. But seeing as I can’t even mention talking to other women in the most platonic non romantic of scenarios I don’t know what more I can do.

Is this trust really irreparable and did I fuck up by asking about M’s dating life?