I’m sorry that you haven’t moved on. That is too bad. You are not the reason he was acting psycho. He chose to act like a spoiled brat with you because he wanted someone else. He is an ass but he has moved on and so should you. It seems you are waiting, like a spider for his relationship to end and for him to accidentally fly into your web. He was not happy with you and is happy with her. If they break up, he will not be happy with you or anyone else. He is going to love this woman for a very long time and there is nothing anyone can do about it.
When I focus on you, I see darkness and anger that have nothing to do with your past relationship. These issues go back to childhood trauma. You have a tough time moving on from just about everything in your life. You must find away to move one with the changes that life brings you. To embrace it. Focus on yourself and what could be in a good way. Stop obsessing over people that choose to be in your past. The fact that you seem to want him to be unhappy again because you want him is a red flag that you are suffering and need to heal. Because when you care about someone, you are glad to see they are happy. It is not your fault that he was acting like a psycho when he was seeing you. It was his. He chose the behavior. He is not, and never will be, good for you. Moving forward is the only choice you have. And it’s the bigger better deal. Trust me.