DTR advice? Exclusive?

I met a guy on okcupid 4 months ago. We've been seeing each other and spending the night every other week. After about a month we both deactivated our okcupid accounts. Recently about 5 days ago on my birthday a friend sent me a screenshot showing the guy im dating reactivated? I'm really starting to get sad. He's been on twice since then. Tomorrow I'm meeting him for dinner. I feel like I need to define the relatiobship now or else I'm going to be stressed and sad about he whole ordeal. I texted him today asking if he still liked me and he said yes.How should I go into tomorrow about bringing it up the whole determining what our relationship is between us?