Decception and betrayal are the two most awful things I think there is to deal with and let go of. Mostly because this usually comes from those we loved and trusted the most.

I am not over it. It still upsets me when I think about it. I think my mind has finally developed a way to not think about it anymore.

Cut yourself some slack. I totally understand the frustration and conflicting feelings when you see him all of a sudden become more engaged because of some other outside force. You know it is good for your son, but of course like "WTF, now you are Mr. dad for some other woman?" But he is just trying to impress her right now. Surely he will fall back into his old ways. but I hope he finds he likes to spend more quality time with his son.

I am happy to hear your new R is going so well. You are taking everything at a great pace. It's a marathon, not a sprint, and you are doing great. Enjoy yourself.