I don't trust my SO

So I take the things he used to do , like being protective over his phone and coming home later than he will tell me , and I kind of point that towards me ex . It's like if he does what my ex does , I automatically think he's cheating and I'm trying hard to not do that , but it's not working . 

My SO has always been kind of flashy . He wears the expensive clothes and jewelry . He goes out to clubs and bars and drink and stuff. He comes home every night , yes . But it's just something telling me he's not being 100% truthful . 

I told him of course . He told me he's not talking to other females , and that he wants to be with me .. But then , tonight I'm walking in the room and he's texting someone . I can't see the number but I seen an emoji . That's all that the person sent ... That's nothing right ? But it's 4AM .... He saves his little guy friends numbers in his phone so it's not a guy . Or maybe I'm over thinking . But , tell me what two niggas are texting back and forth , EMOJIS , at 4AM ... Like , now , as you can see , I'm getting a bit irritated . Smh . I want to trust him but things like this come about .