breakups and makeup's

My boyfriend of almost 2 years broke up with me last Friday because he found out I hung out with a guy he knew while we were broken up about a year ago. We were broken up for about a month and a half before this happened. He texted me yesterday saying he wanted to talk about "us" and asked when I could meet. At the same time, I received a text from my best friend with a screenshot of him on tinder. Idk what to think. I thought maybe he was trying to get back together but now idk if I even want to am I being over dramatic? It's been a week and he's already on tinder...is that all I meant to him? I haven't told him I know yet and we are meeting tomorrow. I was going to ask him if he has tried talking to girls or downloaded tinder this past week and see if he lies. But idk if that's the right approach. Keep in mind, we were doing so well and perfect up until all this shit happened. This tinder thing is fucking me up. What do I do? I know it's easy to say just leave him but I need some actual advice if I want to make things work..