Help with learning to trust

Ladies I will give you a quick run down of the last 4 years or so... so I got pregnant December of 2015 after a miscarriage at 10 weeks. I was over the moon. I ended up in bed rest at 12 weeks (just for a few weeks) I was very unhappy with the changes my body was making. Gained a LOT of weight and had preeclampsia. After I had our son, I had very bad post partum depression. I wasn’t myself and didn’t know if or how I’d get back to that. I was very distant from my husband. I found out he was texting another female (an old friend) I spoke with her and him. Apparently it was nothing and they were just talking as friends do. Because of my insecurities I don’t and didn’t believe it. Also there was a time where I saw snap chat on his phone and we had told either not to have it because I truly feel like it’s nothing but trouble. My trust levels went WAY down.

We are now two almost three years out and I feel terrible that I can not get it out of my mind and it bothers me daily. I still wonder who he is talking to, if he texts any women at work (he is a manager at a car dealership) and so forth. He only shows me love and appreciation but I do not know how to handle this. I make up scenarios in my head and drag them out and take my angers out on him still because of these scenarios. I have seen a counselor and I am still in the headspace that I can’t seem to kick. I need help! Has anyone ever been through this and how did you pull through?