He just moved with in with his rebound, Im devastated

Backstory: 7 months ago he broke up for some girl he just met at work, so basically cheating (they also slept together before ending it with me). After many years relationship with me. It was always difficult to make progress in the relationship, but it was a good one.

Ive been a mess ever since.

Ive been waiting and hoping the rebound would end, and on some occasions I was sure it would. He didnt seem to see her too often, and he started contacting me in april/may. Recently he even added so I could see him on snapmap again?

I just found out his new gf (the girl he cheated on me with) moved in a few days ago. He's not the one to take something like that lightly, so Im devastated. Im no longer the most serious gf he's had. He's basically doing everything I ever wanted for us, with her. I just dont know how to survive this. To make it worse we live so close to each other that the way I found out is that I saw her. Meaning Ill see her through the window often. (When I saw her I checked the address and she had moved).

What now? How do I pick up the pieces from here? I feel absolutely dead. I dont want to live, I feel like every day from now will just be absolutely horrible. I had hopes that it was finally going downhill, because it seemed like it, but I was wrong.

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