@ElizabethNobody,
Hey Hun, I may not say what you want to hear.
But you need to confess. Yes its been 10 months and he still does not know. (I found out over a year after my husbands affairs ended.) Truth has a way of coming out, and honesty does gain some respect back. I caught my husband, but i did not have a CLUE how far the affairs actually went. When he hit full remorse he told me the truth about his actions and backed it up with evidence. Gave me the contacts for his other women and begged me to give him another chance when i knew how to heal. His honesty gained him his second chance.... If he never confessed the full scope, i would have always know that he was caught...he never cared about my feelings. Only protecting his relationship...not me.
In not telling your significant other you are not protecting him. You are protecting you and your deceitful union. You sweet girl did not mean to change the state of your relationship but i can tell from your post that living with this IS now hurting you badly. Yes being honest will hurt him. possible end your relationship, but it won't be better to keep to quiet and have the truth come out later. May be WAY WAY WAY worse.
In any case you are 20, young and can learn from this. Find out exactly why you cheated. That is the only way to be sure you will prevent future cheating and one night stands.
Hugs.... I know this is NOT what you want to hear. But i felt it needed to be said. Your partner deserves to have all the information on your relationship so he knows how to proceed with you and your MUTUAL relationship. In a mutual relationship you don't hide facts from the other. Its not how partnership works. He is 30....His own days of finding a good worthy partner are ticking by. Be honest and endeavor to be worthy of him....Yes he might break it off with you, but you will have done the right thing.
Please think about letting him know, and be ready for him to ask you to leave your work and cut off ALL communication with the other man. If you want him to stay with you, you got a gauntlet of making up to him to do. Start with the truth.