My BF (19M) keeps going against my (19F) boundaries that I’ve spoken to him about many times, what do I do?

I have been with my bf for 3 and a half years, we’ve survived long distance and are now living together at his parents house, trying to save for a house. In 2022, while we were long distance, he met a girl in college and found her attractive which I understand can’t really be helped but it still hurt; he essentially asked me to have an open relationship so he could get with said girl but I said no and he respected that. It hasn’t been the same since as I don’t trust him. Last year I went on his phone as I noticed him looking at other girls right in front of me often. I found half naked instagram models, inappropriate reddit groups, OF tiktokers and open porn tabs, I confronted him about it and he said he’d stop. He didn’t as I found them again a few months later, I’ve found things 3 times since then but I’ve delved deeper to find him looking at dating sites, ai photos undressing people he knows and celebrities he likes and AI sex chats which I again bought up and I believe he had not done that since but yesterday I found recent tiktok searches for certain models and spicy videos. His excuse this time is that I never look like I want to have sex with him. I struggle with BPD and am severely depressed at the moment with the stress of his family, moving, starting a new job and now this again. I’ve never rejected him, even when we were long distance and I just don’t know what to do anymore. I have signed into his tiktok now and am checking everything - I know it’s wrong but I’m at my wits end. He just seems to try to get better at hiding everything. I have no where to go and no money to leave him, I can’t move back in with my own family since they have no room anymore. I just don’t know what to do as he is my first boyfriend and honestly my only friend, I’m tired of talking to him about it since he just lies to my face and acts like nothing happens.

What do I do?