Bf cheated but I later find out more.

So a year ago my bf cheated on me. He was the one to confess. I took him back after 6 months. He said it was just a one night thing and he was drunk. So the only reason why I took him back was because he told me he cheated and because he said it was a one time thing. Since we got back together he has completely changed into a better man. I never been so happy with him. A little over a year passed and last night I brought up the past. I haven’t brought up the past in forever. Idk what got into me. I was just so emotional. So I asked him if he was telling me the truth about it only being a one time thing. After going back and forth for a bit he confessed that he hooked up with her multiple times. I was tooken back by it and I instantly regret bringing up the past. I was so happy with him and now I don’t know what to do. He has gotten my full trust back and he changed for the better and I never been happier with him. But hearing this news sort of makes me view him differently. Like if this past year was a whole lie. Idk I’m saddened by this news. I told him to please leave me alone for a few days and that I need to think about everything.

Please don’t judge me for bringing up the past I know I shouldn’t of but I honestly don’t know what got into me last night.

Ladies any advice?