How to stop “snooping”?

So I don’t know if I’d call what I do snooping but all I know is I need help. I’ll give you a little history of what happened in the past. Last year my boyfriend betrayed me through text (didn’t meet up with the girl in person but definitely betrayed me through his words of what he said to this other girl.) I had found out about it through a notification that popped up on his tablet. (At this point I had snooped, I’ll admit but for good reasons.) The notifications would go to all his devices, for example phone and tablet. Fast forward to today, he forgot his password to download apps on his phone and had to reset his password which logged him out of the notifications for the tablet. In reality, this is nothing to be worried about and no problem. After this happened I started feeling nauseous, anxiety, stress, I couldn’t sleep, my heart kept beating fast, I felt shakey and couldn’t relax. Since last year, I’ve worked on stopping to snoop and have been doing well. As long as he’s logged in and getting notifications on all devices I don’t feel a need to snoop and haven’t. But as soon as he stopped getting notifications on all his devices I literally felt sick. This is a problem. Why can’t I just mind my own business and not care. I felt so sick for days to the point where I logged him in myself to get notifications on all his devices, which I know isn’t right, but since I did that I haven’t even looked at his notifications. I could care less when he’s logged in. Why do I get this feeling? Is it stemming from the betrayal that happened last year? Is it just me being crazy? How can I stop caring about if he’s getting notifications or not? It makes me sick and it’s a problem not only for my relationship but also for my mental health. If it ever came down to it I would feel more comfortable with him staying logged in but adding a passcode or something because I don’t know why staying logged in bothers me so much or where it’s stemming from. Please help me figure this out. We’ve been living together and been dating for over 5 years.