Looking at his list, I’m gonna bet you five dollars right now that he has had an OW from the start of this.
He’s just trying to justify his behavior by turning you into the cause. Trust me, neither your heavy walking or your teenage boyfriend are responsible for his affair.
He doesn’t get to have the illusion of you waiting around as plan B. He doesn’t get to inhabit your home and his separate life. Set those good boundaries and treat him as you would if you were divorced - he needs to see that future.