Three months on, it's pretty torturous trying to decide whether to take him back and try to work past it.
@grass321
In my experience, it actually takes a few years post-discovery to finally know your true mind.
I saw someone up-thread say it took her 7 years. It was nearly 5 for me. It's impossible to figure out while your head is still a mess and everyone is desperately trying to fix things. It's only when you're finally long passed it, and detached from the emotions of it, are you able to look back at the situation and the aftermath and see it. Then you get to decide if the person you see now is actually someone you want to be with.
It took me that long to see how genuinely entitled he was as a person. About so much. He was very much a "I deserve this" type of person. He had an affair because he believed he deserved to have something that would make him happy. (The reason he was unhappy was because I was grieving at the time for my mother and my misery was bringing him down 🙄). He was so upset when I ended things because he thought we were happy and the "incident" was so far in the past that he couldn't understand what my problem was now. Blah blah blah. He was happy, yes. I had just slowly stopped caring.
So, my advice is to take your time. If you want to try to work through it, do, but also be prepared for the damage done to the relationship to be terminal without either of you realising it yet. It really depends on the reason it happened (the type of person he is) and how he handles the aftermath (if he gets annoyed at you getting upset when, in his opinion, you should be over it by now).
It was a slow death for mine, but in the end I was able to walk away strong.