Sometimes I'm worried my boyfriend only stays with me because of our son..

Ive caught him talking to other girls while i was pregnant nothing past hey beautiful kinda thing he was on POF and then kik that one was the one where he talked dirty to one girl and she sent him nudes.. but i forgave him but told him i didn't trust him fully. So anyway fast forward and our son is 4 months old and i see his ex who he loved called him on facebook then he called her back 2 days later and they talked for 10 minutes. Then she was blocked on his facebook. When i confronted him about it she saod she just wanted to see how he was doing and he told her he was happy and that was that. But i just feel like he doesn't love me like he use to like he only loves me because i had his son and everytime i ask him he says im the only one he sees in his future and that he loves me but idk i just feel like he thinks he can't leave because of our son. I could just be overthinking because of the past but idk what to do