She already started another relationship

Hey everybody, (male, 31)
I have had a relationship of 13 years, we had ups and downs as in every relationship I think. Only this year I got depressed and my ex too, so that was not a good combination. I took the step to break up, because we were often in a fight and we didn't feel the love anymore.

Just after we broke up, she wanted to continue and I thought it would be better for us to move on without each other.

But after only 2 months, she already started another relationship and I miss her and want her back. I do not tell her this. Feel like I live in hell, because we actually had a beautiful relationship before this time, build up something beautiful together. I realize I took the decision to fast to break up. But the worst is that she treats me like air, she doesn't want to have to do anything with me.

We loved each other for 13 years and after 2 months she doesn't feel anything for me anymore. I don't understand that.

Anyway. I try to survive everyday. Can somebody give me some motivation, share what you think about it?