You went through your boyfriend’s phone. How do you regain his trust?

“Years ago I caught my boyfriend cheating on me by using a fake facebook profile. We made up, but a few days ago I went through his phone and found a dating app on there.
When I brought it up, he got angry and told me that I betrayed his trust. I immediately felt terrible. He’s the only man I’ve loved. I know what he did was wrong, but I shouldn’t have gone through his phone.
How can I regain his trust?”