How can I find the strength to leave after his infidelity?

I recently discovered that my (26F) boyfriend (28M) of a year slept with a friend shortly after we began dating. I discovered the information, he didn’t tell me. I told him I needed space to figure out what I wanted to do, and he has been reaching out and telling me that he will do absolutely anything to regain my trust, how he takes full responsibility, etc. I believe that he would never do it again and is remorseful. Before discovering this our relationship was actually perfect - it was the healthiest and most loving relationship I’ve ever been in. I know that I should leave, but I’m still so deeply in love with him and can’t find the strength yet to end things. How do I navigate figuring out what is best for me while I’m still so in love with this person?