How does a person process being told to wait on them, and then finding out behind their back they got engaged?

My ex and I were trying to get back together for the sake of love, and for the sake for the kids. When bam, I got an order from the state that my childrens father could not see them until, he was investigated for an allegation concerning one of his children, and did not find any evidence of abuse. The problem is, this went on for 8 months. I tried to stay and touch, and when he got discouraged tell him that he would be able to see his kids once the investigation proved his innonce. Well, in the meantime, he started seeing this chick, because he could not see me. They grew close during this time. Well, anyway, as time went on they lifted the allegation, and he was free to see his kids. The backfiring part was, I found out that he liked this woman so much he decided to get engaged. This woman is about 15 years older than him, and looks like she is pushing 60. I have just been wondering how does a person process this? I thought we would be together! Then he just kept saying Im engaged, but if we are meant to be back together we will be! I am really angry about all of this!