My partner partner of 18 years had a one night stand, we were in a bad place. He intended to tell me straight away because he believed himself to be a good person, but couldn't do it.
I knew something had happened. 6 weeks later his guilt and another drunken night out and he started to tell. He thought a minimised version would allay his guilt and lessen the chance of me dumping him. Problem was, the minimised version was worse to me than the real thing -,' I met some one really special and it made me question my feelings for you, we only had one brief kiss' versus 'I was steaming drunk, this pretty girl paid me attention, I was flattered, we snogged the face of each other and had a seedy grope before I realised what a wanker I was and stopped'.
It took weeks to get the full story, and it was the lying that had hurt the most, he can make mistakes, we all do, but to calculatedly lie and manipulate someone you are supposed to love, and who is giving you a chance after you have fucked ip, that is hard to forgive.
Nearly 4 years later, I don't really care about what he did that night, but the loss of respect caused by his lying I wonder if I will ever get over. I have hardened towards him, in someway I wonder if I actually still love him.
Only you know if you can get over this, but the thing is you don't have to decide now. Why not say to yourself I will hold off making a decision for 6 weeks, or 12 weeks or however long you feel is right. You can ask for some space if you want. Or say yes I am going to work at it then change your mind if it doesn't feel right. It's your choice