My gf (19F) has massive insecurities and I (20M) don’t know what to do

Title pretty much gives the gist of it. I (20M) met my gf (19F) off my college’s Instagram page about a month before we went to school, then in person the first week of college at a dorm welcome event. We moved very quickly, possibly bc of the high emotions of such a large transition. For the first few months everything was great, we were both falling in love with each other and our school and she made me happier than I had guessed possible. Then during Christmas break, while she was back home on the East coast, I took a 3 day trip with my friend group from hs for New Years to Tahoe, where one of my friends (20F, lesbian, for context) has a cabin. This friend group was myself, one other guy, and 5 girls. My girlfriend saw a post my male friend made of the trip in my tagged posts and blew up. I had told her I was going on the trip but hadn’t mentioned specifics of who was going bc at the time we hadn’t figured out who was available. She said it was a betrayal to go on a trip I knew she would have a problem with.

That fight lasted many hours and she would periodically bring it up again. Since then she’s only gotten more and more insecure, partially due to social media. I recognize my part in that, but I have changed it many months ago. But she still brings up my “transgressions” on social media (I.e, liking scantily clad pictures of friends, never commenting), as well as little things (I.e., my mentioning a female coworker saying something funny) and says some godawful things. In fits of rage, she has said I’m a pig, I’m just like all other men, and she’s clearly not enough for me. I have never insinuated anything to that idea and I try my best to make her secure in our relationship by dissecting her insecurities and whether her being upset at the little things is fair. For context, her father cheated on her mother while she was in hs and I believe this is a large source of her insecurities and fear of my straying. Her parents are now divorced and she lives exclusively with her mom and older brother. Ironically, her best friend and roommate (20F) seems to be a pathological cheater and has been unfaithful to every guy and girl she has dated since I’ve known her.

Because I am still in love with the woman my gf was when we first got together, I’ve stayed and made all the compromises she’s ever asked of me. I deleted over 130 women off my Instagram and blocked an online friend (19-20F) I had been friends with for 9 months before we started dating bc my gf viewed our relationship as “inappropriate.” I met this friend once in person through a mutual and ended up hitting it off once we started texting. We got to know each other pretty well and it was a pretty great friendship. We gave each other advice on life, school, and generally had a wonderful time talking. I think perhaps it progressed into the “talking stage” before my gf and I met, but it never went beyond that and when I started talking abt my gf and how great she was, my friend was genuinely happy for me. When my gf found out abt this friend and how often we communicated, she got livid and demanded I block her, after some back and forth, i agreed to block her bc I could see where my gf was coming from. I figured that would be the end of it but she still hurls my now ex-friend’s name at me when she views an interaction I had with a girl, whether it be talking to her for literally 20 seconds in a dining hall or simply being in an assignment group with a girl, as disrespectful. She has begun to recognize that her behavior is incredibly toxic and hurtful to both of us, and because she doesn’t want to feel that pain, but also doesn’t want to lose me, she wants to change it. But even though she recognizes it, she still gets stressed out and upset at little things sometimes not even related to girls. For example, I went to a get together with my friends this weekend and had a cigarette for the first time. I hated it and since I made a commitment to never smoke over a decade ago after learning my grandfather who died before I was born at 52 smoked 3 packs a day, I will not again. But I bowed to peer pressure once, and when I told my gf the next day, I thought she would jokingly admonish me or tease me about tasting like a smoker. Instead when I told her she shut down for about 10 minutes, as she often does when upset, and said when she finally came out of it that my doing this thing I swore not to, it makes her question my faithfulness in our relationship. I have been nothing but faithful in our time together, so this rubbed me the wrong way. I was going to stay over at her room that night bc her roommates were out, but after mentioning the cigarette at dinner, I got exasperated at yet another instance of her taking something inane and blowing it out of context and decided to prioritize peace and quiet for the rest of the evening.

I have no doubts that she loves me and wants to be with me, but dealing with her insecurities and stretches of anxiety is exhausting. I am pursuing a high-commitment double major and am an ROTC cadet, so my free time is already severely limited due to school and career obligations. I still find time every day to be with her, eat meals together, study, and talk, usually at least 2-3 hrs a day. But as of late much of that time has either been in silence as we work or very loud as she screams at me for something inane that happened months before. I have told her she needs to change this or our relationship can’t continue and she seems to understand it. But she also says she doesn’t know how to change and is worried she’s just broken. I don’t believe anyone is beyond the capacity for change and so I’ve given her chance after chance. It’s been about a month and she’s made some progress, but also has had some incredibly bad moments that are honestly the worst since we’ve been together. In that time I’ve become more and more resentful towards her bc of the damage she’s done to our relationship, so I am also prone to getting upset when she shuts down with no explanation. My question is whether she can truly change after being set in her ways for so long (14 months since Tahoe trip) or whether it’s time to call it quits. I don’t want to leave her bc when she’s not upset our relationship is great, but I also recognize how much stress she’s bringing to my life. Can she change in a meaningful and permanent way or is our relationship not going to survive this? If not, how can I let her down in a way that is respectful and calm, so neither of us hate the other?

TLDR: My (20M) gf (19F) gets upset almost daily about little things based on past issues. She can’t seem to accept that I’ve changed and have gotten rid of the things that stressed her out. Is there a chance she will see that and return to the woman I fell in love with, or is that over and it’s time to leave?