you were harsh and straight to the point

Sorry if the post came across as harsh. I felt it was stern.

To just speak when I am spoken to and leave it at that. I think for a week or so he needs to know I am very disappointed and upset by doing that

That's giving the 'cold shoulder'. That doesn't resolve problems, it just creates an icy tension. It's much better to discuss what you're feeling.

You see I found out they have been at it for 3 years last night.

Oh. That whole revelation sucks, I know. It makes you feel as if everything you thought was real was but an illusion. It makes you feel your whole world is pulled out from under you.

It's really part of the same bomb that was dropped before, though you're finding out about it now. Handle it the same way: don't dwell on it, deal with the here and now, keep your focus on you and moving forward. Tell yourself it's OK for you to be shocked and dismayed and to feel terribly about this because it is a terrible thing, and that you're not going to keep on feeling terrible because that was then, it's not your fault, that it's all H's doing, and what you have is again, the here and now, and you have the opportunity to create a better life for yourself.

If H brings her up, you need to say something to stop him mentioning the OW to you.

Nonchalantly change the topic rather than show an allergic reaction to the mention of the OW.

My H says that I am his friend and he wants to tell me about his hurt of losing OW.

It may be difficult, but if he wants to discuss something that is hurting him, as in the case of losing the OW, then if you can be there for him to listen and validate, you may strengthen his emotional bond with you.