Finding out you were cheated on

My boyfriend and I have been together for almost three years. We have a 7 month old daughter together. Our relationship has been fine.... we’ve had some ups and downs but for the most part we’ve been doing good. I recently looked through his phone and found out some photos of a girl who was over at his apartment around 5 months into our relationship.. I confronted him and he eventually told me the truth that they did hook up once and he felt horrible about it and regretted and blocked it out of his head. He told me he never wanted to tell me because he didn’t want to lose me and nothing since has happened with anyone. He felt remorseful. I didn’t see any evidence of anything else happening or going on since that has been shady... he’s never come off to me like that. In the beginning of our relationship we didn’t see each other allllll the time, things were a little rocky here and there as we were both going through some shit. But here we are about 3 years later and I am just NOW finding this out. Of course, I’m broken and hurt. I have no words for the hurt and emotional pain I feel right now. I told him that I wish he would have came clean because I know I would not be here today. As in with him still.. I don’t know what to do. Like. I feel like I just need to think about everything and take some time. I don’t know if I should continue this relationship or if that’s enough for me to call it quits. I’m super conflicted I guess. I’ve been so emotional and upset. I just don’t know how I’m ever gonna live with this if we’re together .. please give me some insight. Now, during this quarantine is when I need people the most and I can’t have that. And it just sucks. I’m sitting here crying alone wishing I could talk to my mom or someone in person.. I’m so embarrassed by this because I already told my sister and I’m sure it’s gonna get around.