<human>: Give me the gist of the text in a nutshell

I was with my ex for 5 years. 3 months ago, I realized that I wasn't happy anymore and I didn't know what to do.

We talked it out for a long time - over a month. We both loved each other, but we agreed that we weren't happy anymore and we both wanted to be on our own for the first time in our life (I've been with him since I was 18, he has been a serial monogamist - I was his 6th girlfriend, he was my 1st boyfriend.)

When we did part ways, he moved out and moved to another city close by. In the last few weeks, we both cried and he told me he would always love me. We also discussed the possibility of getting back together down the road, when we both were on the same page.

We broke up 2 months ago. A week ago, I found out that he started dating a girl he works with a week after he moved out. 

Foolishly, I called him to let him know he broke my heart and how embarrassed I was for missing him and wanting to get back together when he was happy with a new girl. He said he was sorry for how everything had turned out, but he made it clear that he no longer loves me, and would not ever want to get back together. I asked him if he was happier with her and he said yes, and how she is such a selfless, positive person..etc. etc. He made a point of telling me how they go for runs and hikes together - (he became more active at the end of our relationship, and it bothered him that I didn't want to go for a run at 7am with him.)

So, here I am, feeling like he "won" because he moved on first and is happier with another girl. I don't understand how someone can walk away from a 5 year relationship so quickly and completely write that person off. I'm still holding on hope that he will breakup with her and tell me he made a mistake.
<bot>: Had a mutual-ish breakup with my boyfriend of 5 years. He moved on a week later, now I regret the breakup.