My mom was in a similar situation.

My dad was with my mom since they joined the military. Shortly after they met, they married. They had me a few years after that. When I turned 3, they had another baby girl.

And then my mom found out he was cheating on her. With a woman named Beth, who was (and is) mousy, married, and living in Michigan. We lived in Virginia. Every so often, my dad would leave to go to Michigan for "work" and hook up with Beth. He left my mom homeless and stranded miles away from family with a 3 year old and a 4 month old.

Flash forward about 8 years. My dad was with another woman. They got married, and had a little girl. 3 years later, he was cheating on his wife with another woman(call her Susan). (Fortunately, my dad was not contributing to this family financially, and did not leave her homeless and without support. After he left my mom, he stopped working for himself. He mooched off of women who fell for him)

He was with Susan for a few years, and had a baby. I really believed this time would be the time he would stick around. She was young, beautiful, and had a very high-paying job. Everything he looks for. Well, this new daughter turned 3 and, you guessed it, he was found cheating. AGAIN. With the same woman he cheated on my mom with.

The point of me saying all this, was to give you an idea of what my mom, my dad's ex wife, and "Susan" have all done. After my dad was found cheating on one of them, they'd reach out to the previous women he had cheated on. My mom, his ex wife, and "Susan" all talk now, keeping each other supported and updated on their lives without my dad. It did take them a while to warm up to each other, but eventually, they did it. It's sort of like a "clique," where if you are done wrong by my dad, you're welcomed in.

I have no idea if you are willing to try and see this man as another pawn in your ex's "game," per se, but I know it helped my mom, etc.

As far as him trying to act smarter, better, and cooler than you, consider that your ex most likely was feeding him a bunch of bullshit about you.