I found a dating app on his phone

Let me just start out by saying sorry this is so long. Ok so my husband and I have been together for over 8 years and going on our 1 year anniversary. We are so happy to have our own home and our doggies and we're looking forward to this coming summer to start trying for a family. We both have great jobs and have everything that we want pretty much. So tell me why last night while he's passed out on the couch and we have both our phones on the TV tray, his phone lights up with a notification saying "Steph likes you✅". I'm like wtf?? So I grab his phone and open it up. Now I'm not one to snoop because we have full trust in one another (not quite anymore) so I'm hoping it's an app for his hobby (he has a salt water aquarium) well it's not. It's all set up like bumble or some shit. So I go to his conversations and there are girls messaging him and him messaging girls. Honestly I didn't see any flirting. It was all kinda "what are you up to?" "How's your evening going?" I know his ass was feeling guilty. By now I'm standing in the bathroom so I can read everything and sure enough he wakes up and walks in on me "why do you have my phone?" "What are you looking at?" "I have things on there I don't want you to see" (future surprises since our anniversary is coming up). Now he's trying to take it out of my hands to which I say well what are you hiding? Where don't you want me to look???? Why the fuck do you have a dating app?? He acts so dumb I have to fucking pull it up. He must have been hiding that deep in a folder because when I showed him he got all mad and quiet and didn't want to talk about it. I'm in absolute disbelief! I never thought I would ever be in this situation ever! And pushing him and yelling at him and I finally get him to sit down so we can talk about it. He says he didn't do anything, he didn't meet with anyone, it was just talking. Back story this this random act is when we first started dating we were young, I was 16, young and dumb, I cheated and of course he found out and it was the worst mistakes I ever made and it took a long time to gain his trust but we got through it and it never happened again. And will never NBC I'm an adult and I vowed to love and cherish him till I die. Anyway he said he saw this guy comment on a friends post and it brought him back to that pain so that's why he did it. I still can't believe it. I walked away and went upstairs to shower then went to bed, I kicked him out of the room I didn't want to sleep next to him. And I was to tired to yell at him like I wanted to. He was very upset with himself about it all. Crying and punching things saying "I didn't mean to hurt you" ugh. I don't know what to do. I'm a very forgiving person but I don't want to just let him off the hook at the same time. Honestly I keep having to remind myself what he did.