May of been cheated on???

Okay, so... My bf and I have been together for a year and a half. We have talked about marriage and kids and all of that stuff for our future. But I was bored one day and was on his phone (I usually don't go through it idk why I did) but I found Snapchat messages from a year ago (we would've been together 5 months at the time) and it said from him "Mm nice, can't wait to put my cock between those" I confronted him about it and he apologized a billion times and said that he never met up with her and said that he was a different guy then and that I changed him and he didn't realize I would affect him this much. I told him I didn't think I could do this bc I didn't know if he actually loved me and he legit started crying and kept saying that he understands but about how much of a stupid thing it was. He hasn't contacted her since that day and he blocked her right in front of me. Do you think I am just holding a pointless grudge on something from a year ago?