34F suspects 39M being into younger friend after 1 year of dating
I (34F) entered a 1 year relationship with a 39M after being fwb for a year. We have recently separated after living together to go back to fwb for many reasons. Not the best idea as it's already bringing up feelings again, especially the one of a newer 'friend' and him having done something together.
For context, this girl is 26F and a newer friend, I never felt she was a dependable friend but good for chat and going out. I was doing a travel sabbatical during our FWB stage fall 24, and I know they ran into each other on a night out, at the time I didn't think of anything of it as I trusted them both. After we started officially dating in 2/26, we had a bit of a spat and ended up meeting out on the town all 3 of us and other friends. We end up having after drinks at his apt downtown, and they were having playful banter that seemed a little too flirty. I was drunk so I could have been reading into it, but I don't think I was. I asked him about it on our way back to my place and he got SUPER defensive. Couldn't believe I would ask that, he was NOT into her at all. It led to a big explosion because I called out the defensiveness a guilt and he ended up storming out. Fast forward we work through it and end up living together, but it's always in the back of my mind.
I end up not seeing this friend very much after things get serious as we're in different chapters of life. The guy and I break up but delay moving out a couple of months but agree to still be exclusive until he's out of the house as it was fairly amicable separation. He goes out one night 1/26, where apparently said friend saw him sitting at the bar with another girl a little too close. She doesn't tell me though until we go out for drinks 4/26, and when I ask her she says she doesn't know why she didn't tell me, she was drunk, she didn't want to start any drama. I asked her if he flirted with her when he told her hi, and she hesitated to think about it before ultimately saying no. And she was getting nervous like I would say something and I asked her why she cares what he thinks? She said I'm right she shouldn't. So another redflag for her.
Come May she invites me to a pool party, and takes a picture with me in the background talking to her gay friend (who beelined for me as soon as I walked in) and posted it to IG saying "she forgot to take pics at her party". I feel this was intentional all around as he follows her on IG. And then later that night when we're at the bar, she asked me if he's on IG all the time bc he views all of her stories, and she thinks he does it to see if I'm with her. I wasn't on my phone to know if she posted that story before or after we had that conversation, but it was close to it when she posted that. And I find it personally messy to make it look like I'm talking to another man for him to see without my consent to creating drama. I don't think it was an accident either because this is a girl who's trying to be an influencer, her posts are curated and this was a bad shot of people sitting at her table with me right in the middle of the background, this was intentional, I just don't know if it was to be messy in general, or she wants him to go for her.
ATP, I already plan to take a step back from her, but I just want to know if my gut was right all along about the two of them. I know it serves no purpose to know, but I want to. Whats my best avenue? I do plan to ask her next time I see her in person what that post was about to try and salvage some of the friendship. But I'm not sure if there's a better way to be strategic about getting the info I'm looking for.
TLDR; I think my boyfriend may have hooked up with my younger friend before we started dating and had feelings for her he'd never admit to. And I think she has feelings for him too and is trying to sabotage anything that's left between me and him. How do I go about finding the truth?