How do I expose the affair

[mb28]

I remembered a couple of other things my H said to me during our last convo on Friday night:

H: I know I'm hurting you
M: Yes
H: It's like I'm doing to you what you did to me 4 years ago

M: I didn't say anything, but I wanted to say this isn't even as bad as what I did to you. 4 years ago we we're fighting over something I don't even remember. I blurted out that I didn't love him anymore and that I haven't for 2 years and wanted a D. Then I went on to say how we would split things up. We didn't sep and in fact I apologized the next day and told him I said that stuff out of anger. Then I thought everything was fine after that, boy was I wrong.

H: When you did that to me, that is when I started to detach from you and let go
H: I don't want to lie to you anymore
M: Lie to me about what?
H: Pause--- About how I feel and about the D
H: I don't know when and if I'll ever be able to come back. It could be tomorrow or never and I know you won't wait forever.

When I turned down the invite from H today, he asked me what was wrong. I told him I wasn't feeling well, which is the truth. He didn't seem to care either way.