Trusting my partner

I feel like my last relationship played with my mind, but now i'm just scared to lose who I am with. We've been together for a while, and he goes out of the country for 2 weeks every year to visit family. I'm only worried because he lived over there so all over his social media he has people from over there. I trust him, but after reading some of his past messages from before we were dating. I feel a bit scared, because girls with boyfriends would still talk to him. I know I should trust him, but the feeling that he can do something without me knowing bc i'm far away scares me. Is there anything in specific I should talk to him about? am I overreacting? Please no judgement, i'm just scared.