OP, I’m sorry this is hard but two and a half years is a long time and you must focus on yourself rather than them. I say this with care, having been through the same thing. They are still together, now with two new half siblings for my DC, and my DC have no idea of the history. (In my case a confirmed affair and she was much much younger).
a few quick thoughts- don’t assume everything is happy or better for them or will stay that way in the long term. They will be living with the lack of trust, with the hit of reality after the affair buzz, and she will almost certainly want her own kids, meaning he will be back to screaming nappy changing phase while you are hopefully gaining your freedom.
but more importantly, you need to release your emotions - grieve, accept, rant and rage if you need to, so you can move on. The fact that you are still feeling this after two and an half years is understandable, but suggests you are a bit stuck, with unreleased emotion that you are holding in. Write if all down, read it and honour then burn it…. Or rant and punch some cushions….whatever you need to. accept every feeling as legitimate. The anger, self pity, injury to self esteem, all of it…. It is all ok, but you have to accept and feel it in order for it to flow out and release you.
And then focus on yourself- your wellbeing, getting to know yourself, embracing the positives and potential of your new life. I know this is hard when you are managing most of the care and responsibility, but you get to build your own home now, how you like. You got rid of a loser. Now you get to carve your future with your kids. You have a blank canvas to draw on. What do you want to draw? Discover yourself anew. Thus can be anything from working out what colours you want to paint a wall to trying tango dancing, to just enjoying and noticing the love and peace you can share with your kids in the evening.
and her? She is not comfortable- she looks away…. Good. Let her. You are the one who has your principles. And you have nothing to apologise for or feel bad about. There is no need for you to look away. Let her be the one who feels uncomfortable. Take your space. Hold your head up high.
sending hugs.