I am so sorry to hear you have been put in this situation. You didn't ask for it, yet here you are, forced to engage with a whole set of issues arising from your husband's choices.
I am picking my way towards the end of the first year since my husband's disclosure of an emotional affair, which he embarked on with someone he discovered a connection with during a similarly difficult time.
I decided to make a go of repairing the relationship, and in some ways, one might say it's working: we're still here and everything is continuing as normal. The OW is more peripheral in our lives, so not quite as intensely involved as your DH's OW.
But I feel different. While we dived headlong into working on the relationship and experienced some positive things as a result (more honest communication, spending more quality time together, realigning our goals etc), I notice that I feel differently about him on a profound level. He did something to me which I know I could never have done to him. I understand the ins and outs of how it happened but I have stopped trying to will myself to forgive him. I'm OK with not being able to commit to forgiveness. I'm becoming more relaxed about the idea that I'm still quietly on the fence, and may still decide to bail. He doesn't know this, and I don't feel a need to discuss it. We're not talking about the EA or OW regularly anymore, I don't even think about it all the time, but I accept that I carry feelings of hurt and resentment which continue to make themselves known, a bit like a few bits of gravel in my shoe, never not there.
Making the decision to stay or go should be a long-term thing, which you grow into as you see the aftermath unfold, not something to jump to while still in the throes of pain in the first months following a disclosure. One thing which I didn't foresee is that, during a more recent period of personal challenge, I find I'm pretty short on empathy for DH. I feel for him, and make an effort to help him sort out the thing which is bothering him, but I do catch myself thinking: "Less than a year ago, you rationalised causing an immense amount of suffering for me, and here you are, suffering and expecting my support and labour." I'm observing it; this time last year I would have poured myself and my energy into helping him, firmly believing I was helping us. Now, I see that he is often a little entitled and self-centred.
I guess I have become more comfortable with observing the long game, knowing now what I didn't really understand before, that the effects of affairs are systemic and take longer to work themselves out than those of us who opted to give our relationships a second chance often realise. It very much helps to know that I could leave tomorrow without too much disruption to mine or the DC's life.
Oh, and I still have pangs of absolutely, unashamedly, viscerally hating the OW, unable to fathom how she could do what she did to me and our DC. I know the 'idea' is that one ought not to feel angry with one's spouse's affair partner, as they're weren't the one who promised you exclusivity, but I think that's a load of crock and I don't give myself a hard time for 'wrong-think', I think it's pretty natural. It comes and goes, it is what it is.
Wishing you clarity and courage, OP.