This whole thing, G, it's not a linear process. You'll feel yourself doing great for a while and then cycle back through all the anger and sadness of grieving.
It's perfectly ok to have those sad days. You love your H. I would worry if you didn't feel sadness anymore.
Your M was real. It happened. All of it. And no one can take those memories away from you. Ever.
The detachment word we read everywhere on the board...it's no easy thing. Remember it is also a long, non-linear process. It will come in layers, over time, and not without pain.
Use the sadness to validate what you knew was real. Use the anger to propel you forward to the next level. Then let those wash over you, and don't allow those emotions to camp out for too long.
The thing is, the OW is a just bandaid. He kinda has to say things like "best friend" because if he didn't, how could he justify doing such a horrible thing to his family? I mean, who does that? Crazy, that's who.
She can not hold a candle to you. I have seen it many times over, and experienced it myself. She truly isn't worth one thought. Don't give her any power. Keep focusing on you, because you're what matters.
