How do I (26M) regain trust with my partner (31F)?

I have been dating my girlfriend for just about 2 years. Very early on in our relationship a mutual friend told me that she has cheated in a past relationship and when I confronted her about it she was open and honest but I still always think about that in the back of my mind and we talked early on how for me trust needs to be built as the relationship grows.

This past month however feels like everything we built has been spiraling downwards. About 3 weeks ago she went to a river to tube and told me that It was going to be her and 3 other of her friends that are all women and one of their boyfriends. I was completely fine with that but later in the night after tubing was done she texted me that “there are no Ubers available so she’s stuck on her friends time” that friend is the one who picked her up. I knew right there she was lying but didn’t want to say anything over text so I waited until she got home which was around 1am and I confronted her about lying about not being able to get an uber. She didn’t really know what to say. That’s when I found out there were other men that came with to party and drink with them. I then got upset and it turned into an argument for the fact she lied about who was going and about wanting to go home but not being able to.

The following week was her birthday which was a Wednesday and she decided to have a little party at a apartment complex pool, (where neither of us live at) and is a place she knows I don’t like due to last summer she was drugged there, has had multiple men text her/hit on her that live there and 1 of them being an ex hookup she had before we started dating. I work weekdays so the plan was her and her friends go there during the day and after work I would pick her up from the pool and take her out to dinner for her birthday. Well when I got off work and was about to pick her up she canceled the dinner and ended up not coming home until 10pm really drunk. I told her I was saddened that she canceled dinner on me and how I wanted to see her. I asked if the apartment guys were there a she was a little hesitant at first but admitted and then I asked if her ex hookup was there and she said yeah. At the point I was furious, I’m not sure if that’s just jealousy or trust issues I have but I asked to look through her phone and she had deleted text messages from that guy on her phone that day and claimed she didn’t remember deleting them. It was anything inappropriate but I was really hurt that my girlfriend chose to party with her girlfriends and the guys at the apartment complex instead of doing a dinner/date with her boyfriend. I also explained to her that deleting texts even if it wasn’t anything bad is still alarming for a partner in a relationship.

This past week was another breaker and why I’m writing this to see if there’s anything I need to do or if I’m crazy for being upset and on the edge of the relationship currently, but basically I’ve been in my head all week about the birthday incident and I noticed that she had all these messaging apps that I didn’t look through when I looked through her phone the previous week all I looked at was iMessage but I saw that she had telegram WhatsApp and another messenger app. So 2 days ago just us 2 went to a concert and went out drinking and when we got home I asked if I can look through those messages (I know I shouldn’t do that and it sounds crazy but I needed to just so I can be at peace). Well I could tell she was nervous when I asked but handed over her phone and the first app I opened had 2 spam messages recently both were in 2025 and the 3rd one down was from before we started dating but when I clicked on it it was videos of her and a past relationship having sex. I again lost it immediately and drunkenly said some harsh things to her which i regretted in the morning but we haven’t talked much since. She claims she forgot she even had those videos but in my mind it doesn’t make sense why there would be 2 random spam messages recently and nothing else until those messages from 2022 and my gut is telling me she wanted to keep those videos for whatever reason. I also never opened up the other 2 messaging apps after what I saw on the first one.

Besides this past month our relationship has been great and I love her. But I need to know what I or we can do to build trust back and get over this hump in our relationship. Thanks