How to get over feeling insecure

This guy I’ve been talking to finally committed to me and I went through his phone last night because I was curious.

I found a bunch of girls tinder profiles screen shotted and a couple of pictures of other girls he talked to before he committed to me.

Even though he chose me and clearly doesn’t do that anymore I still can’t help but to feel insecure :(

How do I get over this feeling?

Thanks