I (18M) am having trouble trusting my gf (18F) around my bestfriend (18M), what should I do?

I want to preface by saying I never wanted to be controlling in my relationship with her ever and I 110% trusted her to not cheat or do anything with anyone ever.
I (18M) am struggling to trust my girlfriend (18F) around my bestfriend(18M). Just a bit of backstory, we of course have had friends of the opposite gender before we started dating, and I didn’t want her to rid those friends, I actually eventually became super close to a few of her guy friends. However, I had a few female friends and she absolutely despised them, even after meeting them and wanted me to block them. I of course didn’t but just to make her happy, I didn’t fully cut lines with them, rather just talked to them a little less. However, about a year and a half into our relationship, one of her closest guy friends asked to fuck over text and she kinda said something along the lines of “lmaooo” or something but when she asked again she said “Ya I don’t think (my name) would be okay with that lol,” this guy played dumb saying he forgot we where dating. She didn’t tell me until after 30 minutes after. It took some convincing but I had her block him. That response to that text just did not seem approirate at all given the fact that she told me if a girl ever asked to, she made it very firm she wanted me to say no, not being appologetic at all, which I have done once to a girl in public. However, about a few months later irronically, one of my female friends did the same thing, however she called me and told me while my girlfriend was actually asleep. I sort of got uncomfotable and told my friend I’d be right back. My gf and I actually had a big date that night we had been planning for months and after calling her and waking her I told her what I should do and I followed every instruction she gave me, from the word to word text she told me to send to her to immediatley blocking. I had also caught her deleting a text string with another guy while I was sitting next to her while she was showing me stuff on her phone. She just said he sent texts to her she thought I wouldn’t like. She offered to block him and I said yea if that was the case.
I never really thought of that much of anything until summer of last year me and my gf both started working together at the same job as camp counselors on a local farm. I was a farm hand and was kind of promoted to a camp couselor while a new kid took my spot who we will name Q. Q was the same age as me and my gf an we always talked and had lunch together and stuff, when it got to the point where me and Q both hated our jobs, I was a much better farm hand while he handed the kids much better than me, so we eventually switched jobs which was fine with our boss so Q and my gf worked together while I was just a farm hand, and I was completely fine with it, until I started noticing my gf not posted picks of work of the kids or anything but pictures of Q, even saying he looked cute to my face in one of his pictures. It was weird but I just ignored it until she started driving him home a few times since he had only had his permit at the time. Me being a farm hand and her being a couselor meant we both worked completely different shifts so I arrived early and left early while she arrived late and left late. That was also weird but it was a little bit harder to ignore until the point where I noticed her texting him a lot, even when it was just me and her hanging out. Very flirty texts to the point where I told her I was uncomfortable, she got mad at me and it kind of turned into a fight till the point where I said “Do you like him or something?” and she just stayed quiet for a minute until she kind of just told me she did and she couldnt stop thinking about him. I’d like to skip most of what we talked about but basically I asked what she saw in him that I didn’t have and she mostly just said how he looked and also how he gave sort of fatherly vibes when they where couseling the kids at the camp. Stuff like that. She was breaking down throughout the entire thing and went from ragingly angry to extremely broke. As she was telling me the things she saw in him I was just sitting there emotionless. It took a couple months mentally but I was still with her, albeit she was very changed after that. We did cut ties all together with Q, both of us.
That takes us to now, where me, her, and my best friend we will call J (18M) all hang out very often. J has been my best friend for as long as I could remember, after going to different high schools we kept in touch but didn’t hang out as much as we used to after that. J ended up going to the same high school as my gf and he was sort of how I met her. We where playing video games one night while a friend of both of ours kind of invited himself with her out of no where. She claims she used to hang out with him in a friend group but he said that they really didn’t. It sort of tells when they where left alone in the beginning of us three hanging out they where both very awkward, but now its weird. Me and my best friend fight like brothers and even when its just us bantering with each other for fun, she usually sides with him, sometimes exposing personal stuff I didn’t want him to hear but I told her in confidence. Me and my best friend also have classic cars, not anything we are extremely car show worthy proud of, but just projects we like to wrench on. We often fight for fun over who has the better car and she often sides with him saying how much better it is and while many might not care, when you’ve sunk thousands into a car you try to make work and look good and you s.o. makes fun of it, it hurts man. Other little things like she yells at me like a child in front of him but when he does the same thing that she yelled at me for, its a joke and something they can both laugh over. She also seems to always want to go out with him because me and her “don’t do anything fun anymore” even though every time we come up with a fun idea, she usually always ends up inviting him and I never have a say in it. I love my best friend but sometimes I just want to hang out with either her or him alone. A few months ago I was out of state, she asked if she could go shopping in town with someone and I said to go right ahead. I thought she’d go with one of her girlfriends but she went with him instead. I said it was cool but I was uncomfortable given the past with Q. She said she’d just go to these three stores and I said that was fine. I didn’t want to sound controlling but I urged her to please just only go to those three since it was uncomfortable with me. She said of course. Fast forward 4 hours later and she ended up going to 6 stores, one of which was in a completely different county. I said that hurt because I was already uncomfortable with the situation and she promised she would only go to the three but she went to double that. It started a whole argument that lasted a day but she did eventually apologize, and as did I. They went out for food a few times where she promised only food and she did, even though I was still uncomfortable each time they did.
I really don’t want to be a controlling bf but every time shes left alone with him, they arent awkward anymore and I get theyve become super close but its still extremely uncomfortable given the couple other stories and especially including the Q story. I fully trust J and I know for a fact he would never ever do anything as shitty as Q did and try and take her from me or anything. What should I do? Don’t sugarcoat any comments either, if I sound like I am being controlling than tell me.
Please don’t post this shit on any tik tok subway surfer reels or anything either please, its quite embarrassing for me.