Am I just crazy

Hello all, First post here. I am currently in a 2.5 year relationship with the last year being long distance due to my girlfriend joining the Reserves. My previous 8 year marriage ended with me being cheated on, and I want to mention this because I feel it is an important part of the whole situation. One time shortly before my girlfriend left, I had this crazy sudden urge to look through her phone. We never do this usually and respect each others privacy. I did this while she was napping, and while she did have some conversations with other men, they were extremely platonic. I felt terrible after I did this and talked to her about it. She was mad but at the same time said she understood because it was probably baggage from my previous relationship. Fast forward a year to now and the past few months have been very tough. I have visited her a few times while she is going to school for her military trade. Once, she introduced me to her group of friends. They were all male, and I expected this because her trade class has one other female in it that she does not get along with. Everything get fine meeting two of them, they were cool and respectful. The last one showed up late and my girlfriend appeared to be upset because he brought a girl with him that she said she does not like. Now, before we left, we were signing out and another shipmate of hers said “I’m surprised your not signing out with *previously mentioned friend that showed up late*”. This threw me off a bit but I figured since they are friends they likely sign out together as a group. Now, I don’t know if that set me off and I misinterpreted things, but him and my girl seemed slightly flirtatious in their conversations. Basically after I left I pretty much blew up and was very accusatory of the situation and told her not to make contact with him again. We fought about this for weeks because it is her only group of friends and she would basically be isolated. After weeks she finally agreed grudgingly. Two weeks later, she confessed that they never stopped hanging out and he is one of her best friends at the base. This freaked me out even more and I felt extremely hurt. Previous to this, we texted and FaceTimed all the time. Now, she is super distant and barely contacts me. She had a controlling partner in her previous relationship. I think I have fucked up big time, and I’m trying to learn to control my insecurities and baggage from the previous relationship. She now goes out with him plus others in a group and is getting crazy drunk and stuff. I am fighting these constant feelings of insecurity and jealousy. We talked about it and I told her I was sorry for being so controlling and jumping to conclusions. She said we will get through it, we will not break up, but she may seem cold and distant for a while while she processes everything. I am looking for general opinions on the situation, am I crazy for thinking there was something suspicious? How can I control this crazy anxiety and sadness I feel during this low contact period?