HELP Boyfriend thinks I’m plain stupid

Hi all. So recently my boyfriend has been acting funny and I noticed was talking to someone through Snapchat. I always try to play around and snatch his phone and take silly pics of him and lately he’s been snatching it right back and being protective over it. I got curious because this isn’t like him and I checked out his Snapchat while he left his phone laying around. I know.... not cool but curiosity got the best of me. Anyways I see no girls in his recent page and then I take a pic and see what his actual recents that you can’t delete and tamper with are and there’s a girl named “Angela” we’ll say. I click on her name and she her username. I add look her up and add her on my phone and her name comes up as “Queen B💛👅.” So this definitely means my boyfriend changed her name in his phone to Angela. Anyways, fast forward and we are chillin and I quickly grab his phone and pretend to take a snap of our cats being silly and then I’m like oh ?? Who’s Angela? And I ask calmly not in a way to feel like I’m accusing him... and he’s like Angela? I have no idea who Angela is... And I’m like okay no worries I was totally just curious, I’m not upset or anything. He gets incredibly defensive/angry and saying I’m accusing him and questioning his trust. I keep trying to tell him I was simply just asking who she is, no big deal and then we still continue to argue over it.. His excuse sounds like total bullshit ! How does a random user just appear in your recents. Anyways, he’s still holding to the fact he has no idea how it even happened lol what are you guys thoughts? This all sounds so sketchy. I’ve never had a reason not to trust him but this all doesn’t add up and his reaction gives me a reason to question my trust with him.