Sorry in advance for this long post!

So me and my boyfriend recently got back together after being separated for 2 months. Sunday night, I had the instinct to go thru his phone and I found a message thread between him and some random number. They made plans to meet up that night to go smoke together. The plans were initiated around midnight and she texted him saying she got home around 4am. I questioned him about it and he swears up and down nothing happened and they just smoked. FOR 4 HOURS AND NOTHING HAPPENED???? Idk what to do. I love this man so much and I simply don’t know what to do. I’m debating on texting/calling this girl bc I feel like she’d be honest with me but I’m scared to find out the truth. Would y’all take him back if nothing happened or would y’all simply cut it off?