So, For back story two almost three years ago my boyfriend almost cheated on me (but I still considered it cheating but it didn't get past sexting because I found out via this girl sending me screenshots) with this random woman that added him on snapchat. We moved past it and seriously nothing has happened since but last night she added him on snap again and he said he wanted to add her back just to troll him. I had smoked alot and he was giving me examples I thought were funny. He said he was gonna say "How's the new year still trying to get guys that are taken"? And just generally spamming prove it when she said that she wanted him or whatever. I don't remember all the examples but they were all funny and ok to me. I hear nothing of it then she adds me again and I say haha oh she added me again. He instantly panics a bit like saying I'll block her right now idc I'll do whatever you want just say it. And I'm like why're you freaking out? Why would you have to block her thats a bit sus like thought you were just trolling her? Like we agreed nothing you wouldn't want me to say to a guy. And he said "I might've gone a bit too far now that you say that." Even though we had actually agreed boundaries since this happened before and that's why I agreed because I trusted him to do that if he so wanted. But then she sent me a message and he demanded to see it or at least see me open it. I deducted that he had gone too far but not sure how far is too far to him and she has sent me screenshots before so its probably that right? I feel like if I open it and its messed up its kind of on me for agreeing but I also feel like you're a grown adult and should know the difference between trolling and just leading someone on/full on sexting.
TL;DR Boyfriend said he would troll a girl who has sext with him before and I agreed, when she texts me suddenly I shouldn't look at the messages without him.