believer

Can you clafify some things, you mentioned above that you filed for divorce - did that ever become finalized? I am guessing not because you are still referring to him as your husband.

Are you still in counseling? couples? individual? Would be curious to know if the skills you learned during your sessions are still being applied.
It appears that your husband made a mistake, moved out & realized it was wrong. It appears that he tooks steps to make it right - by leaving the other woman, going to counseling, etc & trying make amends. I am not condoning what he did what-so-ever & I am sure you were crushed to find out where he went & with who.

It comes down to a matter of trust- do you trust your husband? No one is asking you to forget what happened but you need to ask yourself if you can forgive & move forward.
If you would like to still work on your marriage & your husband is willing as well. I would speak to him and explain that you still have feelings of doubt. Maybe you can think of things that he could do to reassure you that he only has eyes for you. If you are uncomfortable with him receiving emails from the other woman, tell him, if he loved you, he would respect that & want you to feel as comfortable as possible.

I would hate for you to get hurt again, I know how it feels & it's not fun. However, if you feel that your husband is making a sincere effort, then I think it is worth giving a 2nd chance. When something like this happens once it can be called a mistake, if it happens a 2nd time then there is no mistake about it & you can loose him right then.
good luck