<human>: Can you give me a shortened version of the text?

My boyfriend(19m) and I(19f)  have been together for a little more than 2.5 years now.  We met in high school and had fun but when we left for college we went to different schools.  The first year apart wasn't great but we made it through to the summer and things went back to normal. About a month into our second year of college (still at different schools)  I started getting attention from another guy.  I had gone to high school with this other guy and we were kinda friends so I kept talking to him (he also does not go to the same school as me).  Some of the conversations got into that awkward gray area where the line between being friendly and flirting is crossed.  During this time things with my boyfriend got a little messy so we decided to take a little break from the relationship.  During the break I continued to talk to this other guy but when my boyfriend and I got back together I stopped talking to him completely.  I just last night told my boyfriend about what had happened with the other guy(he had known about the guy trying to hit on me but he didn't know that I was talking to him).  He now says he doesn't trust me that much anymore because he considers that gray area cheating and if I screw up again we're over.  How do I make this up to him and get him to trust me again?
<bot>: Wondered into the gray area with another guy how do I get my bf to trust me again/ how to I make it up to him?