Am I crazy?

So i’m 19 and my boyfriend of almost 11 months is 18 and ever since i got put on birth control (nexplanon implant) back in august, my emotions have been out of wack off and on. It’s starting to get a bit better until he did something that i feel will be forever in the back of my head while we are together. A month or so ago he told me a few times that these people at his high school (i’m in college) have been saying that this girl that he used to talk to before me is going around spreading rumors that they have hooked up before. Why she was doing that? I have no idea (not to mention she has a boyfriend). I have my boyfriends login to instagram and i get notifications for his stuff as well as mine. As i’m doing homework, i see that he gets a request for a dm on his instagram account which he usually never gets. I click on it because i’m curious of who it is. The message is gone. Luckily i remember a few parts of the accounts username. I look them up still on his account and they are blocked. I realized that this is the boyfriend of that girl who was making rumors. I immediately text my boyfriend asking him what’s going on. He claims that guy was cussing at him in dms so he just blocked him. I wasn’t believing that was the case. I looked the girl and her boyfriend up on MY account and i have them blocked (i was following her to begin with). I ask him why he blocked them off of my account and he flips out saying “keep them blocked”. Something is up. I blow up his phone telling me if he doesn’t tell me what’s going on i’ll ask them myself. He explains. He says that he slid up on that girls snapchat story confronting her and asking her why she was going around saying that kind of stuff to people. He then says he was trying to catch her lying because she was denying it by asking her if she wanted TO HOOK UP AND THAT NO ONE WILL HAVE TO KNOW. While he is typing this out i get impatient. So i took it upon myself to ask these people myself to hear what they have to say on my spam account that he doesn’t have access to. The boyfriend of the girl says that my boyfriend was asking her to hook up and saying she had a “fat ass” and this and that. I didn’t know what to believe until my boyfriend was shaken in tears knowing he made a mistake of trying to catch someone lying. I could tell he was telling the truth but it still hurts me to think of him talking like that to other girls. I am still thinking about it and it’s been a week even though we aren’t speaking about it anymore and have moved on, I’m still trying to get over these thoughts of him actually cheating on me.

Someone help?