How do I handle this

There’s this boy who I went to school with that I kinda had a crush on. I had a feeling we’d eventually evolve into being more than friends and I was right.

His attendance wasn’t good so I didn’t see him much but every time he did come we always spoke, laughed with each other, and just had good conversations.

Anyway, I made a Snapchat post and he swiped up. Since then we’ve spoken everyday. I went to his house one day & met his parents. His parents were nice and seemed to really like me. I was at his house for a while so around 8 we left his house. We stayed at a nearby park for a while.

I went to his house a few tines and we would cuddle which led to making out then having sex. Last night I snuck out, he met up with me, then we went to his house.

I took my sweater and layers off so I was in a tank top and my leggings and he was in just his boxers. We were cuddling for a while then had sex. After a few hours we were just looking at stuff on his phone. He was going through his Snapchat memories and I saw videos or pictures of his on a girl. As soon as we saw it he scrolled fast. I said “mm who’s that?” And he said “it’s just some girl. That was from a while ago.” He also said that he was on the phone with someone on Saturday until 5 am. I didn’t ask who because I didn’t want to know the truth. He wouldn’t be on the phone with a guy for that long.

I feel like I shouldn’t be jealous because we aren’t dating but I am. He told me that he doesn’t really introduce his mom to anyone but I met her. He has a lot to deal with and has been through a lot and he’s told me like all of it. He really confides in me. He’s really confident but he even tells me his insecurities so he obviously trusts me with his flaws. I just assumed that we were exclusive because of these things. I mean we talk to each other like we’re in a relationship and it feels like we are.

I’m not sure when those pictures were taken but it’s weird that he still has them. In the moment I didn’t really know how to approach the situation and now I can’t stop thinking about it. I wanna wait until I see him again to bring in up rather than texting him or telling him on the phone.

I’m scared that he’ll get upset with me and I don’t want that so what do I say to him to get an answer