Is this sketchy of my husband or am I overreacting??

So I notice my husband is always a bit on edge when I have his phone. It’s like he’s guilty of something and when I grab it to let’s say look at a pic of our baby that he took and start to walk away he gets all “where are you going come here” but doesn’t flat out say like anything about his phone. So he and my sister were getting too close for me for comfort and texting each other every day a few months after my baby was born. He was say like you’re the best aunt to our son he loves you so much it melts me how he looks at you in this pic and you look beautiful. And she would say Aw thank you etc. and she never stopped it. Maybe she liked the attention because she doesn’t get it from her bf. Idk. Anyways. That was about 9 months ago. Well today out of curiosity because he straight up was fibbing about vaping again I looked at his phone and Instagram. Let me just say one good thing is my husband doesn’t know how to hide things well. Like his vape he told me to hide he found the spot and didn’t close the drawer. So I figured it out. Well his Instagram search bar where you search pages and type them in he had an mma fighter girl page who has lingerie on all over and her butt and boobs hanging out. Another search for some girl’s name, another girl who is a fitness girl with her body all out, one of his guy friends, a comedy page, and my sister. Like my sister never posts…. She has pics of herself and her bf and her but wtf is he searching her for??? I am very insecure about this. My therapist I see when I need to said she doesn’t believe anything happened with them or there weren’t feelings like that. She said he is too nice and knows she lacked attention and was just being too nice… I just don’t like that he has these girls that have their bodies out he’s looking at and my sister is on his search too…like why?? Help? Is this me overreacting? He got all annoyed at me and was like you know what this is so idk I’m so over this.