I feel horrible

I’ve been having horrible thoughts about my husband... everything started when I got him entertaining a girl through his phone and we were about to divorce cause I was devastated even though he tried to make it up many times. After a month, he prepared a wonderful dinner with gifts to make it up again and after I asked for his password to see everything he did it and he blocked everyone I don’t like and he said that won’t do it again. But also during our marriage (4yrs) he’s been lying in small things and now I am back with him and I still feel I can’t trust him again. Even when we go somewhere and he buys drinks for us in a store I feel that he is entertaining the cashier or another gurl he is looking at. What I’m saying it’s that I keep having those thoughts about my husband betraying me that is driving crazy even though I know he is trying to do his best . I don’t know what to do. I’m creating crazy stories about him cheating in my mind every time he is talking to girls in the store we are at, or in the beach, or in Target ( cause sometimes I don’t go with him but he goes with our little son, or I just stayed in the car but he doesn’t last long in there). Help! Am I being paranoid?